The GCR built two batches at Gorton locomotive works, during 1921 and 1922, and they also ordered batches from Vulcan Foundry and the Beyer, Peacock and Company. Twenty eight locomotives had been delivered by Grouping in 1923. The GCR found that they were rather heavy on coal - this led to their nickname of "Black Pigs" - although not much worse than other 4 cylinder designs of the time. They were also remarkably quick to say that they had only 5ft 8in wheels and often pulled heavy expresses in the early period of their career.
The last batch had reduced boiler mountings and detail differences to the cab to conform to the new LNER loading gauge. These were classified B7/2. The earlier batches were classified B7/1.
Thirty-eight locomotives passed to British Railways in 1948, but withdrawal began soon afterwards. Some locomotives surviving in 1949 were renumbered between 61702 and 61713 to make more room for Thompson Class B1 locomotives then under construction.
Boddy, M. G.; Brown, W. A.; Fry, E. V.; Hennigan, W.; Hoole, Ken; Manners, F.; Neve, E.; Platt, E. N. T.; Proud, P.; Yeadon, W. B. (March 1975). Fry, E. V., ed. Locomotives of the L.N.E.R., Part 2B: Tender Engines—Classes B1 to B19. Lincoln: RCTS. ISBN0-901115-73-8.