Male Mark IV tank loaded onto a flatbed railway wagon. Notice the earth mound ramp at the rear of the wagon and how the side sponsons have been pushed in. Do you have any more photos of this tank? Do you know its identity number? Where was the photo taken?
Have you got: Haynes Great War Tank Mark IV? The picture is on page 90.
The text is:
A mark IV male with ist sponsons retracted, up against an end-loading platform at the Baker Perkins factory at Peterborough. What it was doing there is not clear.
The location is slightly wrong. Baker Perkins didn't exist under that name until 1923. The works shown are the Westwood Works in Peterborough, which was the home of Perkins Engineers (formerly Werner, Pfleiderer and Perkins but the company changed its name due to anti-German sentiment in WW1). Perkins Engineers was acquired by Joseph Baker & Sons in 1920 and as I've said changed its name to Baker Perkins in 1923.
I have a good idea what the tank was doing there and believe I can narrow the serial number down to one of five or six tanks, but this is on-going research and I won't post on an open forum.