He was the eldest son of the arch-mandarin Maurice Hankey, Cabinet Secretary between 1916 and 1938, and there was no doubt that Robert was born to public service. His father, according to Arthur Balfour, was responsible for Britain's having won the First World War. The son had a lot to live up to.
He was educated at Rugby and New College, Oxford, and he joined the Foreign Service in 1927. He had a talent for languages and became proficient in German, French, Italian, Polish, Romanian, Persian and Arabic. He began his career as Third Secretary in Berlin and later in Paris, but came back to England in 1936, when he was appointed Private Secretary to the Foreign Secretary, Anthony Eden. His next posting was to Warsaw and Hankey was one of the first to learn of Hitler's invasion of Poland. As the German armies closed in, Hankey escaped to Romania.
From Europe he went to Tehran and was there in 1943 for the most significant Allied meeting that year, and arguably of the war, between Roosevelt, Stalin and Churchill. It was the first time Roosevelt and Stalin met and historians record this meeting as the moment the decision was made by the Allies to invade France.
By July 1945, Hankey was back in Warsaw where he became one of the first British officials to learn of the massacre of thousands of Polish army officers in the Katyn forest and he was given the report of the Polish Red Cross and knew of the culpability of the Russians. His next two postings were to Madrid and Budapest.
In May 1953 Hankey set out for Cairo, the ambassador having fallen sick. Hankey was a good choice. His father was a director of the Suez Canal Company. Indeed, the year of Hankey's appointment to Cairo his father predicted that the British were heading straight for disaster and that the Egyptians would take control of the canal.
A group of army officers had overthrown King Farouk and was demanding the evacuation of the British from the Suez Canal zone. Hankey was briefed by Winston Churchill that, if he did nothing else for six months, he should avoid giving anything away. Churchill also said that Hankey should see his role in Egypt as that of a "patient sulky pig". Hankey was to discover that Nasser was intelligent and a man who thought with his head rather than his heart. No better government for Egypt was in sight. But Hankey predicted that there would be a tendency for the Egyptians to make difficulties for the Suez Canal company once British troops were withdrawn. The Egyptians called him Churchill's stooge and a master of espionage.
Hankey's last posting was to Stockholm, and in 1960 he began a long and happy retirement and was appointed permanent UK representative to the Organisation for European Economic Cooperation.
"Robin" Hankey was much loved in Cowden, a small village in Kent where he spent a long and happy retirement. He was a member of the choir - the only tenor - in the 12th-century St Mary Magdalene Church. He was a fit and active man, played tennis well into his seventies and skied until his late eighties.
Robert Maurice Alers Hankey, diplomat: born 4 July 1905; CMG 1947, KCMG 1955; HM Ambassador at Stockholm 1954-60; KCVO 1956; Permanent UK Delegate to OEEC and OECD, and Chairman, Economic Policy Committee 1960-65; Vice- President, European Institute of Business Administration, Fontainebleau 1966-82; succeeded 1963 as second Baron Hankey; married 1930 Frances Stuart- Menteth (died 1957; two sons, two daughters), 1962 Joanna Wright (died 1991), 1992 Stephanie Langley (nee King); died 28 October 1996.