Boeing 707 ushering in the Jet Age. It established Boeing as one of the largest manufacturers of passenger aircraft, and led to the later series of airliners with "7x7" designations. The later 720, 727, 737, and 757 share elements of the 707's fuselage design. The 707 was developed from the Boeing 367-80, a prototype jet first flown in 1954. A larger fuselage cross-section and other modifications resulted in the initial-production 707-120, powered by Pratt & Whitney JT3C turbojet engines, which first flew on December 20, 1957. Pan American World Airways began regular 707 service on October 26, 1958. Later derivatives included the
Giles Guthrie in total. Guthrie resumed flying and captained proving flights of the VC10, including a transatlantic demonstration to Boston. BOAC were permitted to purchase two Boeing 707 freighters during 1965 and after taking full ownership of the BOAC-Cunard joint venture, the two Boeing 707 passenger jets which Cunard Line had contributed to the joint venture (through their Cunard Eagle Airways subsidiary) passed to BOAC. Passenger growth and load factors quickly increased under Guthrie's tenure, and he invested in larger aircraft with more passenger capacity than either the Vickers Super VC10 or the Boeing 707 could provide. Boeing and Pan American World