He married a fellow ex-RMCM student, the violinist Jessie Hinchcliffe, in 1934 and, after moving to London in 1935, first achieved wide recognition at the 1938 ISCM Festival with the Theme and Variations for two violins. At the 1939 festival, in Warsaw, a far more ambitious score, the Symphonic Studies, demonstrated his mastery of orchestral resources, while in the same year the First Piano Concerto confirmed the achievement of "a highly individual language and certain structural predilections"; both were to remain remarkably constant throughout the rest of his career.
Rawsthorne rescored the concerto in 1942, by which time he was doing military service in the Army first in the Royal Artillery and then in the Education Corps; despite this he was able to complete the two contrasted overtures of 1944 and 1945. He was awarded a Fellowship of the RMCM in 1943. With the end of the war, however, he was at last able to devote all his energies to composition, and to be confident of receiving performance: within some five years he had produced four concertos, a symphony, several chamber works and a body of film music, and was thus already among the more prolific instrumental composers of an English generation that included Walton and Tippett. He married the artist Isabel (nee Nicholas, 1912-1992) in 1955, after divorcing Jessie the previous year.
He was made a CBE in 1961, and was awarded honorary doctorates by the universities of Liverpool, Essex and Belfast. He died in Cambridge in 1971.
Barbara Rawsthorne, Alan’s sister, describes their childhood birthdays in Diary of an Edwardian Childhood:
‘The first important event in our yearly calendar was my brother’s birthday which occurred in May. Birthdays were very important... We were allowed to choose the dinner, so the day began with choosing it. We nearly always chose roast chicken and chocolate pudding. Then there were cards and presents delivered by the postman, and others which had been hidden away for weeks in Mother’s wardrobe, always including an “unbirthday present” for the one whose birthday it was not. We didn’t have a conventional birthday party for children, but generally a granny or two and possibly an uncle had appeared by tea-time, and we had a Procession (we were very great on Processions) all around the house from top to bottom, with trumpets and paper hats, finishing in the dining room with a splendid tea, birthday cake and candles!’