The London and South Western Railway T1 class was a class of fifty 0-4-4T steam tank locomotives designed for suburban passenger work, designed by William Adams and built between 1888–1896.
The class were numbered 1–20, 61–80 and 358–367. In typical London and South Western Railway fashion, they reused the numbers of retired or duplicated engines. The class remained largely intact until the 1930s, being scheduled to be withdrawn by 1940, however due the Second World War a few remained in traffic (around eight examples) until the early British Railways years, the final one (30007) being withdrawn in May 1951.
No complete T1 locomotives were saved for preservation, however a boiler from a withdrawn locomotive was found in a factory in Essex and was subsequently purchased for use on a 'new' T1 locomotive. Since September 2004, this boiler has been stored on the Avon Valley Railway.