Gatwick, 1970's:
In addition to those already mentioned:
DC-8 operators including:
Universal
Capitol International
Airlift International
Flying Tigers
In addition:
Aero America (720/707),
Alaska International (L100),
Modern Air (CV-990's)
And of course, albeit not LGW regulars, Seaboard World, with DC-8's into LHR. Also regularly saw their 747's overflying en-route to Frankfurt.
Great days, and such a variety of carrier's!
I'm sure there are many more!