McMillan-Scott was born 15 August 1949 in Cambridge, England, one of seven children of the late Walter, an architect, and the late Elisabeth McMillan-Scott, née Hudson. He was educated privately by Dominican friars. He worked across the continent, the USSR and Africa as a tour director for a US company for several years. He speaks French, Italian, some German and Spanish. From 1973 he worked in public affairs and in 1982 set up his own Whitehall consultancy. His clients included the Falkland Islands Government. He became a member of the Conservative Party in 1967 and joined the European Movement in 1973. He was one of the joint regional coordinators for the Yes to Europe campaign in the 1975 referendum on EC membership.