Sir Kenneth Stowe: Assistant to three prime ministers noted for his work on the Lib-Lab pact and the Ulster peace process

Stowe was a master of disclosure and discretion, and had a talent for bringing people together to achieve progress

Kenneth Stowe was the dedicated and diligent civil servant who orchestrated Harold Wilson's resignation as Prime Minister in 1976, negotiated the Lib-Lab Pact for his successor James Callaghan, put out the feelers that began the Northern Ireland peace process under Margaret Thatcher, and, with Lord (Norman) Fowler at the Department of Health, got the “Don't Die of Ignorance” campaign on HIV/Aids off the ground.

A master of both disclosure and discretion, Stowe carefully sealed the arrangements he made for Wilson's resignation, a long-planned event that took Britain by surprise, in two envelopes, to be opened only after his own death. Stowe stewarded the close-kept plan with such success that conjecture about some exotic reason for the apparently sudden event has continued fruitlessly to this day.

His talents for bringing people together to achieve progress were appreciated not only by Wilson, Callaghan, and Thatcher, to whom in succession he was Principal Private Secretary, but later by others outside politics. He endured late-night negotiations and acquired a lifetime's aversion to the era's working-lunch staples of smoked mackerel, black cherries and ice cream.

Callaghan gave Stowe “the most difficult three months of my life”, with his initial refusal to move into Downing Street, causing security headaches, but he later impressed Stowe as a “great patriot” with the country's well-being at heart. Callaghan noted Stowe's “awesome capacity to distil the essence of conversations with visiting heads of government.”

Callaghan's negotiation of a loan from the International Monetary Fund in 1976 was, Stowe considered, the start of an economic reconstruction that Thatcher inherited, and which put the country's finances in good shape to receive her changes of policy. Stowe attended all the Cabinet meetings in preparation for the IMF deal, and smuggled the IMF's representative in and out of Downing Street.

Stowe believed that Callaghan's 1977 pact with the Liberal Party had “not the slightest element of personal ambition… he wanted to see good government succeed.” It was Stowe who stayed up until 1.20 am on the night of 22-23 March 1977, after Callaghan had gone to bed, to finalise the pact, giving the Prime Minister the news at breakfast.

Stowe blamed himself for failing to avert the misfortune that would forever after be associated with the start of the 1978-79 “Winter of Discontent” of public service strikes – when Callaghan, returning from a summit with the French, German and US presidents in Guadeloupe, denied a suggestion that Britain faced mounting chaos, producing the newspaper headline: “Crisis? What crisis?”

“I let him down,” Stowe reflected. “I didn't go with him to Guadeloupe… if I had been wiser, cleverer and smarter I would have gone to Heathrow and met him and told him to say nothing until he got back to No 10…. He then spent the next three miserable weeks virtually alone in his study, trying to reconcile what was going on with his own profound belief in what trade unionism was about.”

Callaghan was defeated in May 1979, and in the space of six weeks Stowe became a trusted figure to Thatcher, before he was moved to the Northern Ireland Office as Permanent Under-Secretary of State. That trust was to allow him to advance relations with the Irish Republic.

In late 1980 Stowe made a list of gestures the government might make in order to end hunger strikes by inmates in the Maze prison. This was passed to IRA contacts via an MI6 agent, who for the sake of avoiding kidnap waited to receive it in London in Stowe's official car.

Stowe also drafted the communiqué that was released after Thatcher's 1980 summit with Charles Haughey in Dublin. This caused her to tell him, “You have destroyed my credibility with the Unionists”, over the document's declaration that the leaders' next meeting would be devoted to “the totality of relationships within these islands”, a phrase almost exactly reproducing one that Haughey had used. But by then Stowe and the Cabinet Secretary, Sir Robert Armstrong, had established a framework for regular contact, and despite Thatcher's wariness would continue their work.

From 1981-87 Stowe worked with Norman Fowler at the Department of Health and Social Security, in one of the longest partnerships in recent times between a Permanent Secretary and a Secretary of State. It was Stowe, Fowler records, who with Sir Robert (later Lord) Armstrong, the Cabinet Secretary, arranged for Lord Whitelaw to chair a special committee, so spurring on the campaign on HIV/Aids that would become Britain's largest on public health since the Second World War. “Ken was a substantial politician in his own right and knew every byway of Whitehall”, Fowler recalled.

Stowe was the son of a maker of spectacle frames from Dagenham. His father, Arthur, had fought in the First World War, losing a lung from mustard gas. Stowe won a scholarship to study history at Exeter College, Oxford, and began his Civil Service career with the National Assistance Board, helping to provide food and shelter for older or disabled people. There he reached the rank of Principal in 1956, and was seconded to the United Nations Secretariat in New York in 1958, before becoming an Assistant Secretary in 1964 and joining the Department of Health and Social Security as Assistant Under-Secretary of State in 1970, moving to the Cabinet Office as Under-Secretary in 1973.

In 1949 he married Joan Cullen, whom he had met at school, and they had two sons and a daughter. After his retirement in 1987 he served on the commission set up by the South African president Nelson Mandela to establish his country's civil service, and from 1987-97 was chairman of the Institute of Cancer Research. His wife died of the disease in 1995.

Professor Dame Jessica Corner, the Institute's first nursing academic, recalled how Stowe “quietly and wisely” helped her put the case for the importance of nursing in cancer care. In later years Stowe lived with his partner, Judith Phillips, in Herefordshire, and took part in local administration.

Kenneth Ronald Stowe, civil servant: born Dagenham 17 July 1927; CB 1977, CVO 1979, KCB 1980, GCB 1986; married 1949 Joan Frances Cullen (died 1995; one daughter, two sons); died Lingen, Herefordshire 29 August 2015.