Aveling and Porter No. 807, nicknamed "Old Chainey", is a standard gauge 2-2-0GWT (geared well tank) railway traction engine built in 1872, making it the oldest Aveling traction locomotive in preservation. Unlike most of its later brethin, 807's wheels are driven by a chain instead on a series of gears.
The locomotive is currently on loan to the Buckinghamshire Railway Centre on static display.