zLNER Rebuilt Cl.W1 '10000'HOR R3843 Hornby LNER, Rebuilt Class W1, 4 6 4, 10000 Era 3 Having completed nearly 90,000 miles of test running since new, Sir Nigel Gresley's W1 4 6 4HP 10000 entered Darlington Works on 21 August 1935 for what was anticipated to be a major overhaul and modification. During this period Gresley decided that it was time to rebuild 10000 as a three cylinder locomotive with a conventional firetube boiler and 10000 was moved to Doncaster Works on 13