There is the story told at Bolton where an engine crew was booked to work the Friday only Bolton - Euston service which was booked for a Jubilee. The foreman told them to take "727" sitting by the coaling tower and the crew discovered 42727 sitting there; on re-checking with the foreman he insisted that it was "727" they had to take so the crew duly prepared the loco and set off for a hard weekend flogging the Crab with the 12-coach load down the WCML and returning with the booked return on Sunday night. When they duly returned to Bolton the foreman called them into his office for a "right proper talking to" as the stupid b******s had taken the wrong engine. 45727 had been at the other side of the coaling tower and was the engine they should have used but because they had taken the wrong engine the shed had had to put it on the local weekend trip and pw turns - for which it had proved most unsuitable. The full story was told in one of the railway magazines a few years back by one of the crew involved.