He was born in Keighley, Yorkshire, and educated at Balliol College, Oxford. After military service during World War II, he became involved with the Labour Party and was elected MP for Leeds in 1952. This was the beginning of a long and distinguished career, which culminated in his period as Chancellor of the Exchequer (1974-79) under both Harold Wilson and James Callaghan.
As Chancellor, Healey's tenure falls into two parts which are sometimes called Healey Mark I and Healey Mark II. The divide between the two is marked by Healey's decision, taken in conjunction with Callaghan (by then Prime Minister), to seek an IMF loan and submit the British economy to the associated IMF supervision. Within some parts of the Labour Party the transition from Healey Mark I (which had seen a proposal for a wealth tax) to Healey Mark II (associated with a government specified wage control) was regarded as a betrayal. The perception was largely responsible for Healey's inability to command the support necessary to succeed Callaghan as party leader.
Healey's bushy eyebrows and soft-spoken wit earned him a favourable reputation with the public, despite the label of "Silly Billy" which attached to him as a result of the caricature presented by the television impressionist, Mike Yarwood. Those who knew him better commented on his ruthless efficiency as Chancellor. His long-serving deputy at the Treasury, Joel Barnett, in response to a remark by a third party that "Denis Healey would sell his own grandmother", quipped, "No, he would get me to do it for him".
After failing to win the Labour leadership in 1980, at a time when his right-of-centre stance was unfashionable within the party, Healey remained in the background, eventually retiring from the shadow cabinet in 1987, during the long reign of Margaret Thatcher.