Assuming that I can find the date, do you think it would be possible to find out which DC-8 aircraft operated that flight that day. I can't imagine that they were in Gatwick too often, so maybe some of the spotter magazines made a mention of it.
G of N,
Reckon you would find a contact here.........
http://www.gatwickaviationsociety.org.uk
Good luck Planemike........