Sydenham was built in 1895 and is typical of the machines built by Aveling and Porter, Rochester, Kent, for railway use. Aveling and Porter are better known for their traction engines. It is a compound and thus it has a small diameter high-pressure cylinder and a large diameter low-pressure cylinder. Both are mounted on top of the boiler and drive the four wheels via a system of gears. Water is carried in a rear mounted 'tender tank' and fed to the boiler with either the injector or pump.

First home for Sydenham was the Erith, Kent, wharf of Beadle Brothers (later William Cory and Sons). It worked there until 1924 when it was sold to the neighbouring Erith Oil Works, who had it rebuilt in 1931. This firm later became British Oil and Cake Mills. In about 1953 they purchased a diesel shunter and Sydenham was laid up, with the company's other Aveling and Porter loco being retained as a spare.

Eventually, in the early 1960s, Sydenham was acquired by the Enfield Veteran and Vintage Vehicle Society, and ownership was later transferred to the QRS. The loco was temporarily stored at Luton before delivery to Quainton in April 1969.

Sydenham forms an interesting link with former days at Quainton Road Station, in that traffic on the Brill Tramway was worked by two Aveling and Porter locomotives between 1872 and 1894. They were single-cylinder machines and had a maximum speed of about 8 mph, taking about an hour to travel the 6 miles from Quainton Road to Brill. One of these locomotives is normally displayed in the London Transport Museum at Covent Garden.  Whilst that museum is being refurnished, No. 803 Brill, is on display at Quainton.

Sydenham has been loaned to the North Kent Industrial Locomotive Society (Chatham Dockyard) for up to 12 years in return for them restoring her to full working order. This was a good opportunity to have her restored by an experienced team at no cost to Quainton. She will be returned several times when restored so the locomotive can been seen her on home ground, and will return permanently by 2009.

Sydenham is now operational, and returned to Quainton for a "Grand Steam and Vintage Vehicle Show" on the 17 and 18 September 2005.