Between 1965 and 1966, Soames was Shadow Foreign Secretary under Edward Heath. He lost his seat in Parliament in the 1966 election. In 1968 Harold Wilson appointed him Ambassador to France, where he served until 1972. During his tenure as ambassador, he was involved in the February 1969 "Soames affair", following a private meeting between Soames and French president Charles de Gaulle, the latter offering bilateral talks concerning partnership for Britain in a larger and looser European union, the talks not involving other members. An offer the British government eventually refused and that for a time strained Franco-British relations. He was then a Vice-President of the European Commission from 1973 to 1976. He was created a life peer on 19 April 1978 as Baron Soames, of Fletching in the County of East Sussex.