My friend who owns Lindsey
, a 50ft. Mk1 RAF Refueler, has written to say the boat in the photograph doesn’t look like yours, and that it may be an earlier type that had twin petrol engines. The Mark 1’s had 4 cylinder Crosley diesel engines (however, there was prototype that was fitted with twin Crosleys). My friend will make further enquiries and then get back to me.