Only Luton based Britannia Airways operated 707’s and that wasn’t for long. Also a 707 would not be a normal aircraft for that route. I can’t see why any other 707 would want to divert to Luton with its short runway unless the crew had no choice.
The only case I can remember where an aircraft had to divert to its nearest airport that happened to be Luton was when a British Midland aircraft possibly a 737 had double engine problems after take off from East Midlands Airport. I think some seals were missing after maintenance work spilling oil everywhere but that was year later.