No. 550 Squadron was formed at Waltham, near Grimsby, in November 1943, as a Lancaster heavy-bomber squadron in No. 1 Group and began operations that same month. Early in the New Year it moved to North Killingholme - also near Grimsby - and from there continued to play its part in the bomber offensive until late April 1945, when it switched to dropping food to the starving Dutch people.
The squadron had three Lancasters - all Mark IIIs - which passed the 100-sorties mark in wartime operations: EE139 "B-Baker" (named The Phantom of the Ruhr), ED9O5 "F-Fox", and PA995 "V-Victor" (ex-"K-King", and named The Vulture Strikes). Of these three aircraft "B-Baker" eventually logged the greatest number of sorties - 121; it was then sent to a training unit. Another Lancaster only failed to reach its century by a small margin. This was W5005 "N-Nan" (again a Mk. III) which had the misfortune to ditch in the Humber estuary on returning from its 94th sortie.