At first glance it looks as if a V2 has been put on The Flying Scotsman due to an engine failure but knowing the date of this photograph explains all. The first of October 1955 was a Saturday, and Peter Coster in the ‘Book of the V2 2-6-2s’ (Irwell Press) has this to say:
The V2s were worked hard and one of the turns on which one would expect a pacific, the up Flying Scotsman, a heavy train, was occasionally hauled on a Saturday by a Top Shed V2. This was before it became a lodging turn for the A4s, and the V2 was not a last minute substitute but had been actually rostered for the duty. This happened only occasionally, on a Saturday and always with a Kings Cross V2. (-They had no dud V2s at Kings Cross!) If a V2 worked the train on a weekday it would be much more likely a substitute for a failure and especially so if the V2 was not one from 34A.

© David P Williams Archive; Original photograph by Les Perrin.