Sav,
G-BGKJ was the full registration (withdrawn from service 1994). The added picture below from the same day showing that the flight was a 'casevac' mission for an offshore based passenger. Sorry can't remember the details, but such flights were / are not uncommon in the North Sea.
One extra for you, this time G-BEZJ in my garden at the time. Can't say more, have to protect the guilty!!
Both circa mid 80's.
Planko
