Many thanks ORAC! Got in touch with the divers and they're hoping to make a trip to Lough Foyle next year to do a through search using sonar and to take video footage under the water.
Apparently there may be as many as seven WWII aircraft in Lough Foyle. I'm going to take a picture of the Corsair at Myroe (photograh above from 1972) and post it - although as you'd expect, it's in much worse shape than 30 years ago. I'll also try like seafuryfan to get a pic of the firefly at Eglinton.
Thanks again!