Hello Dany,
I have a Sgt. J. N. COCKROFT, R.A.F.V.R., No. 38 Sqn > awarded the DFM in August 1944 and a recent Squadron Leader John Maurice COCKROFT – RAF Coningsby which was also awarded recently (2014):
http://www.raf.mod.uk/news/archive/o...-2014-20032014
Maybe more details from the airman you are looking for can be obtained with this Squadron Leader which was still active.
Your man is named JOHN EDWIN, but I did not manage to find his Squadron or the Base he served on.
Most sincerely
Adriano