This one just popped up on Ebay UK:
https://www.ebay.co.uk/itm/water-bow...EAAOSwknVe0sjC
Remains of a pretty standard 200 gallon water tank, possibly either Bedford MWC or Morris CS8. Except it has a small instruction plate in the bottom left side of the rear locker, identifying the priming point for the power pump. Mine doesn't have that, because it would be underneath the lockers!
Unless my eyes deceive me, the mounting points for the rear locker framework appear to be on the right side, whereas they are normally seen on the left side of the tank. Could this possibly be the same arrangement as the one shown on the back of the C15 below? Does this now suggest the early British water tanks were built in both left and right hand versions, depending what truck they were destined for?
Owen.