I came across this thread whilst researching my grandad's service. He was at Marston Moor in 1941/42 (and served with Leonard Cheshire when the latter was attached to HCU1652 during the 1000 bomber raids on Cologne, Essen and Bremen). I have found this on National Archives' website:
I'm going down in a couple of weeks to view it.
Did you find anything of your father's time there?