The RAF depended largely on US transport aircraft such as the C-47 for most of World War II and it was not until the final years of the conflict that a true British design, the Avro York, finally appeared. Developed by Roy Chadwick in the space of only six months, the York was something of a by-product of the Lancaster bomber adapted for transport duties: it featured the Lancaster's wings (high-mounted) and tail unit (albeit with a third fin) but with a more spacious slab-sided fuselage for cargo and passenger carrying. One of the prototypes famously ended up as Winston Churchill's personal VIP aircraft with prominent square windows, taking the Prime Minister on various trips including wartime conferences in Moscow, Yalta, and Tehran. Production versions were used as freighters and cargo or passenger transports for both military and civil use, neverthless only a few were actually operated during World War II, the grand majority having seen service post-war where they were mostly remembered for their role in the Berlin Airlift, flying almost half of all British sorties.

The prototype of the Avro 685 first flew on 5 July 1942 and was fitted with twin fins, the central fin being added in the third prototype which became Churchill's personal transport with the name "Ascalon". Production units were designated York C.1 and these comprised the bulk of production as military, civil, and VIP transports although a single C.2 was later fitted with Bristol Hercules radials.