LMS Coronation Class

The London Midland and Scottish Railway (LMS) Coronation Class^[a] is a class of express passenger steam locomotives designed by William Stanier. They were an enlarged and improved version of his previous design, the LMS Princess Royal Class, and on test were the most powerful steam locomotives ever used in Britain at 2,511 dbhp.^[1] The locomotives were specifically designed for power as it was intended to use them on express services between London Euston and Glasgow Central; their duties were to include the hauling of a proposed non-stop express, subsequently named the Coronation Scot. The first ten locomotives of the Coronation class were built in a streamlined form in 1937 by the addition of a steel streamlined casing. Five of these ten were specifically set aside to pull the Coronation Scot. Although a later batch of five unstreamlined locomotives was produced in 1938, most of the ensuing Coronation class were outshopped as streamliners. Eventually, from 1944 to 1949, all-new engines would be built in unstreamlined form, and all the streamliners would have their casings removed. The very last of the 38 locomotives was completed in 1948.

The Coronation class was probably painted in more styles of livery than any other engine class, seven in the LMS era up to 1947 and five more during the British Railways era from 1948 onwards. That does not mean that all 38 locomotives were painted in all these different styles; many were specific to just a few engines. The only style that all 38 bore was the British Railways lined Brunswick Green and the entire class was turned out thus between 1955 and 1958.

It was customary on all British mainline journeys to change engines at convenient locations to avoid the lengthy process of re-coaling. The Coronation locomotives were therefore strategically stationed at key points between London and Glasgow, and they would be assigned to the shed at that location. The chosen locations were at London (Camden shed), Crewe (Crewe North), Carlisle (Upperby) and Glasgow (Polmadie). It was only in the latter days of steam that the mix of shed assignments became more fluid.

Whilst the Coronation class was represented at the 1948 British Railways locomotive exchange trials, designed to compare the performances of similar locomotives from all four of the pre-nationalised companies, the representative engine performed disastrously. Gone was any hint of the power that could be unleashed by these engines; instead, uncharacteristically low coal consumption was the target. If the trials were forgettable, other achievements of the class are certainly memorable. Firstly, No. 6220 Coronation held the British steam speed record between 1937 and 1938, 114 miles per hour.^[2][3] It held that record until the record was shattered by 4468 Mallard in 1938. Secondly, No. 6234 Duchess of Abercorn holds the record to this day for the greatest British power output to be officially recorded on an attached dynamometer car, achieved in 1939.^[4] Unfortunately, the most memorable event in the history of the class was the Harrow and Wealdstone rail crash precipitated by 46242 City of Glasgow. This was the second worst rail crash in British history, the death toll being 112.

After a successful decade of operations in the 1950s, the 1960s' modernisation plan was the ultimate undoing of the Coronations. Not only did the increasing use of diesel locomotives make many of the class redundant, but the electrification of the main line between London Euston and Crewe also resulted in their banishment from this important section of the main line as there was insufficient clearance between the locomotives and the live wires. With no useful role to play, the survivors were scrapped en masse from late 1962 to late 1964. Fortunately, three locomotives were saved for preservation, with one of them ending up in the National Collection. As of October 2016, two are static in museums whilst the third is fully certified for main line service.

Contents[]

1Design history
2Construction history
- 2.1Locomotives
- 2.2Tenders
  - 2.2.1Overview
  - 2.2.2Table of tender and locomotive pairings
- 2.3Modifications
  - 2.3.1Double chimneys
  - 2.3.2Smoke deflectors
  - 2.3.3Removal of streamlining
  - 2.3.4The final locomotives
  - 2.3.5Automatic warning system
3Liveries
- 3.1The LMS era
  - 3.1.1Pre-1942
  - 3.1.2Post-1942
  - 3.1.3Table of LMS liveries
- 3.2The British Railways era
  - 3.2.1Pre-1951
  - 3.2.2Post-1951
  - 3.2.3Table of BR liveries
4Shed allocations
- 4.1Overview
- 4.2Table of shed allocations
5Records
- 5.1British speed record
- 5.2British power record
61948 locomotive exchange trials
7Accidents and incidents
8Withdrawals
- 8.1Overview
- 8.2Table of withdrawals
9Preservation
- 9.1Histories of the three preserved locomotives
  - 9.1.1No. 46229 Duchess of Hamilton
  - 9.1.2No. 46233 Duchess of Sutherland
  - 9.1.3No. 46235 City of Birmingham
10Table of Locomotives
11Gallery
12Sound
13References
- 13.1Notes
- 13.2Citations
- 13.3Bibliography
14Further reading
15External links

Design history[]

Although the prior introduction of the Princess Royal class had provided the London Midland and Scottish Railway (LMS) with more powerful locomotives to be used on the main line between London Euston and Glasgow Central, the board of directors were persuaded in 1936 that more such locomotives would be needed, particularly as they were being asked to approve the introduction of a new non-stop service between those cities, designated the Coronation Scot.^[5] Initially, the Chief Mechanical Engineer, William Stanier, planned to build five more Princess Royals, but the Chief Technical Assistant and Chief Draughtsman at the LMS Derby Works, Tom Coleman, argued that it would be preferable to design a new class of locomotive that was more powerful, more reliable and easier to maintain. Stanier was convinced and the drawing office commenced designing the new class.^[6] When Stanier was called on to perform an assignment in India, Coleman became responsible for most of the detailed design in his absence.^[7]

Compared to the Princess Royal Class, there were important differences which would lead to an improved performance. Increased power was obtained by adopting a bigger boiler with greater steam-raising capacity; this included a firebox heating surface of 230 sq ft (21 m²) versus 217 sq ft, a flue heating surface of 2,577 sq ft (239.4 m²) versus 2,299 sq ft, superheater surface area of 830 sq ft (77 m²) (some sources say 822 sq ft) versus 598 sq ft and a grate area of 50 sq ft (4.6 m²) versus 45 sq ft. Also, the steam passages were better streamlined for greater efficiency and, most importantly, the piston valves went up in size from 8 inches to 9.5 inches. In order to allow higher speeds, the diameter of the driving wheels was increased to 6 ft 9 in (2.06 m) (from 6 ft 6in) and the cylinder diameters were increased by ¹⁄₄ in (6.4 mm).^[8] The outside cylinders were moved forward with rocking shafts operating the inside cylinders. Finally, a coal pusher was incorporated into the tender, so the fireman did not have to "bring the coal forward", significantly cutting his workload which was particularly important on the long runs from Euston to Glasgow.
Streamlined version NOT as originally built, but as preserved. Just as the new design was approaching finalisation, the LMS marketing department created a problem that was close to being insurmountable. The London & North Eastern Railway (LNER) had recently introduced its streamlined Class A4 locomotive which had captured the imagination of the public, and the marketing department persuaded the board that the LMS's new locomotives should be streamlined too. This was problematic in that the new design was so large that it only just conformed to the maximum loading gauge for the main line; moreover, it was sufficiently heavy that it was close to the Civil Engineer's maximum weight limit. Nevertheless, Coleman managed to design a streamlined steel casing that hugged the locomotive so tightly that it could still meet the loading gauge. The casing weighed some 5 long tons (5.6 short tons; 5.1 t), but Coleman managed to save an equivalent weight in the locomotive itself.^[9][10]

The casing was tested in a wind tunnel, and retained after it was found to be as good as other forms of streamlining.^[7][11] After introduction it was subsequently found that its aerodynamic form failed to disturb the air sufficiently to lift the exhaust from the chimney, thus obstructing the driver's vision with smoke.^[12]

Construction history[]

Locomotives[]

The first five locomotives, Nos. 6220–6224, were built in 1937 at the LMS Crewe Works at an average cost of £11,641 each.^[13] They were all intended to haul the Coronation Scot, so the locomotives and the special trainsets bore a common livery. The locomotives were streamlined and painted Caledonian Railway blue with silver horizontal lines along each side of the locomotive. The special trainsets that they hauled were painted the same shade of blue and the silver lining was repeated along each side of the coaches.^[10]

In 1938 the second five locomotives of the class, Nos. 6225–6229 (named after Duchesses) were also built in streamlined form at an average cost of £11,323 each.^[14] They were painted in the same shade of crimson lake which had already been applied to the Princess Royal class; the same style of horizontal lining that had been a feature of the first five locomotives was continued, but in gilt. Although the crimson lake matched the standard LMS rolling stock, there was no attempt to apply the gilt lining along the sides of these coaches. A prototype trainset was built with such lining for exhibition in America, but it was never put into service due to the outbreak of the Second World War.^[15]

Stanier, the designer of the locomotives, felt that the added weight and difficulty in maintenance due to the streamlining was too high a price to pay for the actual benefits gained at high speed.^[16] Therefore, in 1938 a third batch of five locomotives (again named after Duchesses) was built, Nos. 6230–6234, without streamlining at an average cost of £10,659 each.^[17]

During 1939 and 1940, a fourth batch of ten locomotives (Nos. 6235–6244) was built in streamlined form commencing with No. 6235 City of Birmingham. The names of cities for the locomotives would seem to have been adopted because the LMS was fast running out of names of Duchesses. These locomotives cost an average of £10,659 for the first five and £10,838 each for the second five.^[18] The names of the cities in this batch were in strict alphabetical order. This came to an end when No. 6244 City of Leeds was patriotically renamed King George VI in 1941.^[19]

The fifth batch, again named after cities, comprised four locomotives, Nos. 6245–6248. These engines were built during 1943 and the average cost was held to £10,908 due to the incorporation of recycled boilers.^[20] During the Second World War, the Materials Committee of the government tried to balance the needs for steel between civilian departments and the War Department when allocating those resources.^[21] Despite these constraints, the entire batch was still outshopped in streamlined form.^[22]

The theme of cities continued into 1944 when another batch of four, Nos. 6249–6252, was built without streamlining. The cost of these locomotives averaged £11,664 each.^[23] A follow-up batch of three locomotives (Nos. 6253–6255) was built in 1946 and this batch attracted an inflationary average cost of £15,460 each.^[24] The problem of hanging smoke was addressed and smoke deflectors were now incorporated into the design.

The final two locomotives were constructed to the modified design of George Ivatt who succeeded both Stanier, following his retirement, and Stanier's immediate successor Charles Fairburn, who unexpectedly died in office.^[25] The first, No. 6256 built in 1947, was the last of the class to be built before nationalisation and it was therefore named in honour of its original designer Sir William A. Stanier, F.R.S.. The unveiling of the nameplate was performed by Stanier himself.^[26] In 1948, the privately owned railways were nationalised and incorporated into British Railways.^[27] It was within this new regime that No. 46257 was completed – in common with other LMS locomotives, 40000 had been added to the original numbers.^[28] The spiralling costs after the Second World War, combined with the design changes, resulted in the individual cost of these locomotives escalating to £21,411.^[29]

Tenders[]

Overview[]

The lack of a handrail on the tender shows that this is an ex-streamlined Type A. The locomotive is No. 46225 Duchess of Gloucester photographed in 1961, so the table below shows that the tender is No. 9799.

The original design of tender, which came to be known as Type 'A' was designed for the first ten streamlined locomotives. These were of welded tank construction and included side sheets extending from the rear of the tender, which had the effect of reducing drag from eddies between the tender and the leading coach. 28 of these were constructed to be coupled with all the 24 streamliners (Nos. 6220–6229 and Nos. 6235–6248) as well as four of the unstreamlined locomotives (Nos. 6249–6252).^[30] In practice, it would seem that the side sheets made it more difficult to access the water filler as well as the couplings.

A second, more traditional design followed for the initial batch of five unstreamlined locomotives (Nos. 6230–6234). Again, they were of welded tank construction but lacked any of the streamlining add-ons. Even without the streamlining Type 'B' tenders were distinguishable from Type 'A' by having a slightly different profile at the front and steps and handrails at the rear.^[30]

The third design, by George Ivatt, initially was Type 'C1' and it was paired with the three locomotives Nos. 6253–6255. It was partially riveted and resembled a Type 'A' at its front end and a Type 'B' at the rear. The design was quickly followed by Type 'C2', which differed from the 'C1' in that it had a lower front edge and was fitted with Timken roller bearings. Only two 'C2's were built, and they were coupled to the last two of the class, Nos. 6256 and 6257.^[30]

Whilst nearly fifteen of the tenders remained wedded to their original locomotives, others received new partners – the very first tender to be manufactured swapped partners seven times. After the Second World War, when the streamlined tenders were de-streamlined, it was difficult to spot any mismatches. The most readily visible mismatches were those of locomotives Nos. 6249–6252 where pre-produced Type 'A' streamlined tenders were married to unstreamlined locomotives.^[31]

An unusual feature of all Coronation Class tenders was that they were fitted with a steam-operated coal pusher to bring the coal down to the firing plate. When this was in operation a plume of steam could be seen rising from the rear face of the coal bunker backwall.^[32] This equipment greatly helped the locomotive's fireman to meet the high demands for power during the non-stop run of 399 miles (642 km) between London Euston and Glasgow Central, when operating the Coronation Scot train.^[33]

Table of tender and locomotive pairings[]

All LMS tenders were given their own unique identity numbers and they tended to be constructed in advance of the locomotives they would be paired with. Hence, they were made in four batches, Nos. 9703–9709, 9743–9752, 9798–9817 and 10622-10624.^[30]

The following table lists the locomotives to which they were attached.^[34] Of note is the fact that locomotive No. 46221 had its tender (No.9816) withdrawn ahead of time in 1962; the locomotive was then paired to the Princess Royal tender No. 9359 until its withdrawal in May 1963.^[35]

showTender no.	Type	Original loco. & style	2nd loco.	3rd loco.	4th loco.	5th loco.	6th loco.	7th loco.	8th loco.	Withdrawn

Modifications[]

Double chimneys[]

Single chimneys were fitted to Nos. 6220–6234 when built.^[36] Following a successful trial using No. 6234 Duchess of Abercorn on 26 February 1939,^[37] these were replaced with double blastpipes and chimneys between 1939 and 1944, the last being No. 6220 Coronation. From No. 6235 onwards, all the locomotives were built with double blastpipes and chimneys.^[38] ^[39]

Smoke deflectors[]

Following a report by George Ivatt in 1945, smoke deflectors were introduced due to drifting smoke obscuring the crew's forward vision.^[11][26] The first locomotive to be fitted with smoke deflectors from the outset was No. 6253 City of St. Albans in September 1946. All the following four locomotives included this feature. The first unstreamlined locomotive to be retrofitted was No. 6232 Duchess of Montrose in February 1945.^[36]

Removal of streamlining[]

George Ivatt's 1945 report also recommended the removal of all streamlining casings and they were removed from the fitted locomotives from 1946 onwards.^[26] It had been found to be of little value at speeds below 90 mph (140 km/h), and was unpopular with running shed employees as it caused difficulty of access for maintenance. The first step towards de-streamlining was carried out during the Second World War when many of the streamlined tenders had their side sheets cut away at the rear of the tender. Many photographs exist showing this measure.^[40][41] The removal of the streamlining proper commenced in April 1946 with No. 6235 City of Birmingham. All de-streamlining coincided with the fitting of smoke deflectors. No. 6243 City of Lancaster was renumbered as 46243 in April 1948^[42] and, as it was not de-streamlined until May 1949, it became the only locomotive to carry its British Railways number while streamlined.

Initially, locomotives that had previously been streamlined could be readily recognised by the sloping top to the front of their smokeboxes, as well as slightly smaller front-facing cab windows.^[43] ^[44] In due course all were re-equipped with cylindrical smokeboxes and larger cab windows, often, but not necessarily, at the same time.^[45]The first locomotive to receive a cylindrical smokebox was No. 6226 Duchess of Norfolk in October 1952. The last one to retain the sloping top was 46246 City of Manchester which appeared with its new smokebox in May 1960.^[36]

Even following the conversion to cylindrical smokeboxes, it was still possible to distinguish some non-streamliners from ex-streamliners. On the former (Nos. 46230-46234 and 46249-46252, but not 46253-46257) the running plates veered downwards at right angles to connect with the buffer beam in the style of the Princess Royal Class.^[46] The ex-streamliners did not have any such connection,^[47] except No.46242 City of Glasgow which was rebuilt in 1952 following a serious collision.^[48]

The final locomotives[]

The final two locomotives Nos. 6256 and 46257 Sir William A. Stanier, F.R.S and City of Salford were given many new features. In order to raise the mileage between general overhauls from 70,000 to 100,000, measures were taken to decrease wear to the axle bearings and hornguides through the use of roller bearings and manganese steel linings. Other modifications included further superheating area, a redesigned rear frame and cast steel trailing truck, rocking grate, hopper ashpan and redesigned cab-sides.^[26][49]

Automatic warning system[]

During the twentieth century, signals passed at danger (SPADs) were increasingly perceived as a significant danger to the public. Only the Great Western Railway truly accepted the challenge posed. Prior even to 1910, it commenced installing Automatic Train Control (ATC), a system where each distant signal was accompanied by a ramp between the tracks with which a shoe on the locomotive would make contact as it passed over it. When the signal denoted "clear", an electric current would pass through the ramp which was detected by the shoe, thereby sounding a bell in the cab. With the signal at danger, the electric current would be cut off and when the shoe detected this it would activate a warning horn. In later forms, the brakes would be applied should the driver fail to acknowledge the warning.^[50]

In 1952, the UK's most disastrous SPAD ever occurred at Harrow and Wealdstone, in which No. 46242 City of Glasgow was severely damaged. The lack of an ATC system on most of Britain's railways was at last seen as an urgent issue. From 1956 the BR-designed Automatic Warning System (AWS) was installed. It was similar to ATC but relied on an induced magnetic field rather than an electric current and featured a visual indicator in the cab. The receiving system was installed on the Coronation class locomotives from 1959 onwards. The outward evidence of on-board AWS comprised a protective shield behind the front screw coupling, a box to house the necessary batteries immediately in front of the cab on the right-hand side and a cylindrical vacuum reservoir above the right-hand running plate.^[51]

Liveries[]

The LMS era[]

Pre-1942[]

Before applying the top coats of paint, the LMS would apply a matt undercoat of shop grey. The first non-streamlined loco was fitted with mock-up nameplates and numbers for each of the first batch of locos which was then photographed to mimic each individual loco. Those temporary nameplates are now in the NRM's collection in York. The ensuing LMS top coats for the Coronation Class came in two basic colours during this period: Caledonian blue and crimson lake. Linings for streamliners involved the renowned 'speed whiskers' comprising stripes emerging from a fixed point in the lower centre of the front of the locomotive to run in parallel along the sides. Non-streamliners carried the standard LMS-style lining.

The first five locomotives, Nos. 6220–6224, were painted in Caledonian blue with banding in silver-coloured aluminium paint.^[52] Wheels, lining to the edges of the bands, and the background to the chromium-plated namelates were painted in a darker blue, Navy or Prussian blue.^[52]

The second and fourth batches of streamlined locomotives, Nos. 6225–6229 and 6235–6244, were painted in crimson lake, with banding in gold lined with vermilion and black.^[52] Nameplates had a black background.^[53] LMS shop grey was carried briefly in service on No. 6229 Duchess of Hamilton from 7 September 1938 until its return to Crewe Works later that year.^[54][55] It was then painted crimson lake and disguised as No. 6220,^[52] in preparation for the 1939 visit to the New York World's Fair. Lettering and numerals for both Caledonian blue and crimson lake liveries were in a newly created style of unshaded sans-serif.^[56]

The non-streamlined Nos. 6230–6234 were painted in a special version of the standard crimson lake livery.^[57] The locomotives were lined out in gold bordered with fine red lines. Serif lettering and numerals in gold leaf and vermillion shading were applied. Handrails and sundry small external fittings were chrome-plated, as were the nameplates, which had a black background.^[57]

Two unusual events have been recorded. Firstly, in 1940 No.6221 Queen Elizabeth had its Caledonian blue colour scheme replaced by the crimson lake, the only such instance.^[58] Secondly, it was often speculated that at some time in the two-year history of the Coronation Scot a crimson streamliner might have hauled the blue trainset. Such an event has, probably uniquely, been captured on film.^[59]

Post-1942[]

No. 6233 Duchess of Sutherland in presevation turned out in LMS Black. Black was the overriding colour for this period, with one exception. Streamlined locomotives Nos. 6245–6248 were outshopped at Crewe in 1943 painted plain black.^[60] The following two batches, Nos. 6249–6255, constructed without streamlining, were also painted unlined black; the lettering and numerals on all these locomotives was in serif style coloured yellow with red shading.^[60] From 1946 onwards de-streamlined locomotives were mostly repainted in black with LMS-style lining. The lining comprised a broad maroon centre with fine straw yellow edging. Lettering and numbers were in a sans-serif Grotesque font, coloured yellow with an inner maroon line.^[61] By the end of 1947, 29 of the 37 locomotives were painted thus.^[58]

The one exception to black was No. 6234 Duchess of Abercorn which in 1946 was painted in a blue-grey colour.^[62][63][64] This represented the proposed post-war livery and the lining, painted on one side of the locomotive only, comprised a pale straw yellow line along the running plate with yellow and black edging to cab and tender. Lettering and numerals used a sans-serif font.^[65][66]

Table of LMS liveries[]

The following table lists the liveries carried by the Coronation class between June 1937 and December 1947.^[67] The blue-grey livery has never been authenticated in a colour photograph.

showLMS No.	Name	Cal'n blue	Shop grey	Crmsn lake	Crmsn lake	Plain black	Lined black	Blue-grey

The British Railways era[]

Pre-1951[]

Early in 1948, before the new liveries for the whole of British Railways had been decided upon, Nos. 46229, 46232 and 46236 were repainted in LMS-style lined black^[58] and No. 46257 was similarly turned out when constructed in July.^[68] Throughout 1948 and 1949 the English locomotives (now under the control of the London Midland Region of British Railways) were repainted in BR lined black.^[69][70] However, the Scottish locomotives based at Glasgow's Polmadie shed, which were under the control of the Scottish Region, were destined for a brighter future. Commencing in May 1948, seven of the class were called in to be painted in "experimental blue". So sudden was this decision that No. 46232, fresh in LMS-style lined black following its heavy general repair, was called back after a mere four days to be repainted blue.^[71] Around this time BR was also experimenting with various shades of green on the other regions.^[72]

The Polmadie experiment was upheld by British Railways in 1949 when the somewhat darker BR standard blue was selected for all its large passenger locomotives, despite the fact that the Great Western Railway (GWR), the Southern Railway (SR) and the London & North Eastern Railway (LNER) had overwhelmingly painted their locomotives green (the LMS by contrast concentrating on crimson lake). Blue was subsequently carried by 27 of the 38 Coronation Class locomotives. The first two to be so painted, Nos. 46242 and 46243 were outshopped in the new colour when they received their heavy general repairs in May 1949.^[73] The blue livery, which was subsequently phased out, lasted until September 1955.^[74]

British Railways undertook a massive programme to establish itself by repainting all its locomotives with their new BR numbers and replacing their previous corporate identity with its own. Gone were the tenders proclaiming the railway companies' logos, emblems and even coats of arms, to be replaced by the stark BRITISH RAILWAYS lettering. The enormity of this task meant that the necessary repainting was not necessarily carried out to coincide with an overall repaint. For the Coronation Class, all locomotives had been through this process by the end of 1948 except for Nos. 6223, 6238, 6248, 6250, and 6252–6255, a total of 29 locomotives.^[75] Only thirteen locomotives out of the 29 received new liveries to accompany their renumbering.

Subsequently, in 1949 a crest was designed to replace the spartan BRITISH RAILWAYS logo. In turn, this would be replaced in 1956 by yet another design of crest.^[76]

Post-1951[]

Preserved No. 46233 Duchess of Sutherland hauls a steam special gleaming in its BR Brunswick Green.
In 1964, No. 46238 City of Carlisle shows off its coat of LMR Maroon. It also sports a yellow 'line prohibition' stripe.

The decision to adopt blue as the standard colour was subsequently reversed and Brunswick green was introduced in November 1951 with No. 46232 Duchess of Montrose.^[77] Between October 1955^[77] and December 1957,^[78] all 38 locomotives carried it concurrently, the only livery the entire class carried.^[79]

In the late 1950s the decision was made that the London Midland Region's main line locomotives could carry the colour maroon. This permission did not extend to the Scottish Region whose locomotives remained green until withdrawal.

The LMR maroon was carried on 16 locomotives from the late 1950s: Nos. 46225-6, 46228-9, 46236, 46238, 46240, 46243-48, 46251, 46254 and 46256.^[78][80] No. 46245 was the first, in December 1957; a further fifteen examples followed between May and November 1958.^[78] The style of lining varied: the first six repaints into maroon (including No. 46245) were lined out in the LMS style; the last ten received the BR style of lining as used on the standard green livery; No. 46247, originally lined in the LMS style, was given the BR style in July 1959; and by November 1961 those with the BR lining were repainted to match No. 46245.^[78]

Because of insufficient clearance between the locomotives and the 25 kV overhead electric wires south of Crewe, the whole class was banned from operating under them with effect from 1 September 1964. To highlight this prohibition a yellow diagonal stripe was painted on the cab sides. This inability of the locomotives to operate on the line for which they were designed was crucial in the decision to withdraw the entire class.^[81]