The London and North Eastern Railway (LNER) Class B1 4-6-0, designed by LNER’s chief mechanical engineer, Edward Thompson, was a mixed traffic 4-6-0 used for general passenger and freight duties. Introduced in 1942, 274 were built by LNER and 136 by British Railways after nationalization in 1948. These locomotives operated throughout the LNER system in England, Scotland, and even on the Southern Region.

Two B1s are in preservation now, No. 61264 and No. 61306. The North British Locomotive Company built No. 61264, which began as LNER No. 1264 until British Railways took ownership in 1948. The only LNER locomotive to survive in Barry scrapyard, it was rescued in 1973 and has been restored to mainline traffic by the Thompson B1 Locomotive Trust.

No. 61306, built in 1948, was delivered after nationalization to British Railways. In preservation, it was painted LNER apple green livery and given the number 1306, which would have been its LNER allocated number had LNER not been nationalized, and the name Mayflower, taken from a scrapped BR built Thompson B1. In the summer of 2019, the preserved Mayflower became the first regular steam operated service to run from London Waterloo terminal in 52 years.