I think the only practical all-metal landplane airliners in production in Britain in 1939 were the rather small DH Flamingo and the very underpowered AW Ensign, the latter given lower priority even in peacetime when production was moved to AST Hamble because of military commitments at the parent factory. The orders for both types for BOAC were completed in 1940/1941.Perhaps the Ensign (re-engined) might have made a decent military freighter but there were no other suitable designs available and by 1941 Britain's situation was so perilous only combat aircraft production could be contemplated Many secondhand DC-2s and DC-3s were purchased by Britain in the US that year