Allen was seriously injured in a car accident at Irthlingborough on 7 January 1948 and had to have an operation. He had recovered in time for the
1950 general election in which his Conservative opponent Major Anthony Cripps was the nephew of Labour
Chancellor of the Exchequer Sir
Stafford Cripps; Allen retained his seat with an improved majority after the intervention of a Liberal candidate. In June 1950, Allen helped to defend Cripps against a Conservative motion which called for the United Kingdom to participate in negotiations on the "
Schuman Plan" to organise European coal and steel production. He sponsored an amendment which refused to enter undefined commitments and stressed the importance of the Commonwealth. After Cripps' sudden resignation, his successor as Chancellor
Hugh Gaitskell kept Allen on as his Parliamentary Private Secretary; Allen had also worked for Gaitskell in Gaitskell's previous position as Minister of State for Economic Affairs. ==Opposition Whip==