Sir John Killick, successively Ambassador to the Soviet Union and to Nato, was a distinguished member of that generation of British diplomats who joined the Foreign Office straight from long and varied wartime service in the Armed Forces. As such his whole active life was shaped by the need to confront dictators: Hitler during the war and a succession of Soviet leaders during the uneasy peace that followed.

John Edward Killick was born in 1919 and educated at Latymer Upper School, at University College, London, and then briefly, on the eve of war, at Bonn University. He was almost 20 when war broke out, and spent the next seven years in khaki, starting in The Suffolk Regiment, serving with West African troops and ending in the Airborne Forces.

By the time he was demobilised in 1948 the Army had put clear stamp on his personality and appearance, which he never lost. Yet combined with such military characteristics as clarity of thought and firmness of decision was another, rather reflective and academic side to his personality, which ensured that his grasp of the essential was supported by a concern also for the circumstances surrounding any issue which came across his desk.

After two years in the Foreign Office after the war, Killick was assigned to the Control Commission in Germany, where the needs of what was still the hungry and battered British zone of occupation highlighted the urgency of putting West Germany together as a democratic state and ally in the Cold War. He stayed in Germany for three years, serving successively in Berlin, Frankfurt and Bonn.

It was the era of the airlift that defeated the Soviet blockade of Berlin, and of the creation of the Federal Republic. In the course of it Killick, still in his early thirties, was reinforced in his belief in firmness in the face of an opponent and, at the same time, in the need for creativity.

In 1951 he was brought home to a junior private secretary’s job, but three years later he was posted to the embassy in Ethiopia, which was and would long remain an almost medieval autocracy.

After Addis Ababa he had a year’s sabbatical at the Canadian Defence College, four years in the Foreign Office department dealing with Western Europe, and a year rediscovering the ways of soldiers, sailors and airmen at the Imperial Defence College in London.

So when Killick was promoted to counsellor and dispatched to Washington in 1963, as co-ordinator in Britain’s largest Embassy, he was well-equipped to deal with the political-security complex that played such a large part in the British-American diplomatic relationship.

He stayed in the US for four years and then came home (his rate of promotion accelerating now) to an Under Secretary’s job in the Foreign Office. Further promotion followed, and in 1971, at 52, he set off to Moscow as Britain’s new Ambassador to the Soviet Union.

British-Soviet relations were paradoxical. On the one hand, negotiations to ease tensions over Berlin and the two Germanys were draining poison from the East-West relationship in Central Europe. On the other hand, Britain’s determination to expel more than 100 Soviet Union spies operating under diplomatic cover in London provoked a paroxysm of real or feigned Soviet anger.

The Russians retaliated, and the embassy in Moscow found itself suddenly and seriously undermanned. Relations with the Soviet authorities, always frosty, turned glacial. It was a time for determination and cool nerves, Killick’s strong suits. He faced up to Soviet provocation calmly but firmly. At the same time, he and his wife brought a very human touch to the life of the embassy community. By the time he left Moscow after a difficult two years, the worst of the froideur was over.

Killick served next in London, as the Deputy Under Secretary responsible for Western organisations. Representing Britain at the Council of Western European Union was part of the job. More importantly, he was preparing himself for one of the Diplomatic Service’s most important appointments, that of Ambassador to Nato. He went to Brussels in 1975 and stayed until his retirement four years later.

Once again, relations with the Soviet Union were paradoxical. On the one hand the Conference on Security and Co-operation in Europe was wending its weary but eventually successful way to better East-West understanding in Europe. On the other, Soviet military expansion, which was to lead to a major East-West showdown over missiles in Central Europe a few years later, threatened the West’s security.

Differences were opening up between the United States and the European members of Nato. The potential for misjudgment was great, the need for cool analysis and calm decision manifest. Once again, Killick played his instrument in the diplomatic orchestra with aplomb. His reward when he retired from the Diplomatic Service in 1979 was the knowledge that he had helped to keep the peace.

His going was marked also by his promotion to GCMG, having been appointed KCMG when he set out for Moscow eight years earlier.

In 1949 Killick had married Lynette du Preez. She came from South Africa, and the couple settled there on his retirement, he serving for some years as a director of Dunlop South Africa. After her death he returned to Britain, where in 1986 he married Irene Easton, known always as “Bill”. He lived out a long retirement in Kent, devoted to the support of the Atlantic Alliance relationship.

His second wife predeceased him. He had no children.

Sir John Killick, GCMG, diplomat, was born on November 18, 1919. He died on February 12, 2004, aged 84.