Sir D'Arcy Patrick Reilly, GCMG (17 March 1909 – 6 October 1999) was a British diplomat who served as ambassador to the USSR and France.
He won a Laming Travelling Fellowship at the Queen's College and was a Fellow of All Souls from 1932 to 1939, the same year as Isaiah Berlin.
In 1942 he was seconded to take up the post of Private Secretary to 'C', Major-General Sir Stewart Menzies, the Chief of the Secret Service.
In 1957 he was awarded KCMG and became British Ambassador to Russia playing a central role in the Summit meeting of 1959 alongside Macmillan and Selwyn Lloyd.
He led the UK Delegation to the Icelandic Fisheries Negotiations in 1960 and in 1964 headed the British party at the UN Conference on Trade and Development.
In 1965 he became British Ambassador to France until 1968[3] when George Brown effectively terminated Reilly's career abruptly and with scant courtesy, having concluded that he was the wrong man in Paris.