After the war, he designed Britain's first pressurised airliner, the Avro Tudor, based around the Lancaster-derivative Avro Lincoln, though few were built and also the Avro Shackleton in 1946. His final involvement with Avro was overseeing the initial designs of the Avro Vulcan (Avro 698) from 1946. Author Harald Penrose describes Roy Chadwick in "British Aviation" as "Artistic with unbounded enthusiasm and unsparing energy, Roy Chadwick was a great designer of intuitive diagnostic ability rather than a scientist, yet like all great masters was in step with the tide of knowledge and contemporary outlook." Chadwick was appointed a Commander of the Order of the British Empire in the 1943 Birthday Honours for his contribution to the design of the Lancaster and in particular for the adaptations he made to it in preparation for the low-level attacks on the German dams, during the Dam Busters raid Operation Chastise. The same year he was granted the Honorary Freedom of the City of London.