wee Ronny....
Was he nicknamed "Bunny"?
Just found a link to this old PPRuNe thread, but on Phantoms so may be the next generation on....
BBC programme "Skywatch" circa 1974 [Archive] - PPRuNe Forums
PS A DFM would have been awarded BEFORE his commission, if that gives you a possible time line....?
There is also something for a 619 Squadron W/C Warren, DFM, but I can't see any reference here....
https://www.facebook.com/619.Squadron.RAF.WW2
Hope one or the other have meaning for you!