The SECR B1 class was a class of 4-4-0 steam tender locomotive for express passenger service on the South Eastern and Chatham Railway.

These engines were originally designed by James Stirling for the South Eastern Railway (SER) in 1898 and designated B class.

Twenty B Class engines were built by Neilson, Reid and Company and numbered 440-459.

When the Southern Railway took over in 1923 they initially gave the numbers an "A" prefix and later added 1000 to them.

Locomotive history of the South Eastern Railway, D.L.Bradley, Railway correspondence & travel society (RCTS) ISBN 0 901115 48 7