Of the 15 newly built A2s, only the first, No. 500, emerged from Doncaster under Edward Thompson while he was Chief Mechanical Engineer. That was in May 1946 and, by the end of the following month, Thompson had retired aged 65. The remaining 14 were built under his successor, Arthur Peppercorn, between July 1946 and September 1947. They had planned to build 25 in total, but Peppercorn cancelled the remainder while he made modifications to the design. His new design became the A2 and the Thompson locomotives were designated A2/3s. No. 60521 entered service as No. 521 ‘Watling Street’ at Gateshead in May 1947 and was withdrawn by BR at Tweedmouth in November 1962.