I am indebted to all you professionals who have taken the time to answer my query - I really didn't think it would generate that much interest !
Meant to say in my OP that I'm almost 'nose-on' to the aircraft concerned so maybe that makes a difference. In case Jonty isn't joking I'll sit under an umbrella ! and 1pudding1 - no need to apologise - I enjoy seeing you guys and sorely miss the Hercs, VC10s, C17s and other guests that no longer go over my house into Lyneham.