Certainly Flt Lt D W Gray RAF was killed flying off Theseus on 13 March 1951 but the book "With The Carriers In Korea" does not list all RAF members of FAA units.
There is another book which lists all awards for Korea and the RAF seems to do reasonably well for a change. The contribution by the RAF to the USAF and RAAF has been commented on but how your g/f's father got involved is anybody's guess. I'd check his medal ribbons for a start!!!!
Old Duffer