Spose this thread should be in H & N
Pan American at LGW saw 707 on regular affinity charters there from as early as the late 1960's (TWA too) along with the likes of World, TIA. Saturn, Universal, ONA, AFA and Capitol.
Any very early flights were likely diversions.
German IGS Jet feeder flights were into LHR with 727's usually based at Tegel but Pan Am had a German presence from early 1950's starting at TempelHof
Boeing 727-200, Airbus A-310 and A-300 operated in and out of Tegel until 1991.
Pan Am scheduled flights into LGW came along many years later (Bermuda 11?) and infact LGW was their last ditch London base until their sad and sorry demise.
Delta had begun operating Pan Am's transatlantic routes on November 1, 1991, becoming overnight a major carrier across the Atlantic. Acquisitions included Pan Am's New York to Europe routes, hub operations at Frankfurt and New York-JFK, and Pan Am's Miami—London and Detroit—London routes.
London operations were from Gatwick airport only; Pan Am had earlier sold its London-Heathrow access and transpacific routes to United Airlines in 1985.