It’s always the one in the background that’s a puzzle, isn’t it - the rear-loading modified Stratofreighter, partly visible in this detail from our TAH 13 picture of Boeing 707 N761PA at Renton, is YC-97A 45-59593.

Of course! The inspiration for Harold the Helicopter: a superb photograph of float-equipped Westland-Sikorsky WS-55 G-ANUK at London’s Waterloo Air Terminal in 1955, against a backdrop of railway arches and the Royal Festival Hall.