Designed by Edward Thompson, Chief Mechanical Engineer of the London North Eastern Railway (LNER), the B1 class was a wartime utility mixed-traffic locomotive for general passenger and freight duties - the LNER equivalent of the ubiquitous LMS "Black Five". A total of 410 were built between 1942 and 1952 and were to be found throughout the former LNER system in England, Scotland and, for a short period, on the Southern Region. 

The first member of the class was named "Springbok" in honour of a visit by South African leader Jan Smuts, and the first 40 were all given names of various breeds of antelope, but with so many being built most were not named.

No. 61264 was completed and entered traffic on 5th December 1947. Used on the many express passenger services between Nottingham, Leicester and London (Marylebone), 61264 was withdrawn in November 1965. Rather than being scrapped immediately, the loco became Departmental no. 29 and was allocated to stationary boiler duties, still at Colwick.

No. 61264 is owned by the Thompson B1 Locomotive Trust, and has worn a number of different numbers and names in preservation including 60134 "Chiru" and 61005 "Impala"