Education
Williamson was educated at Tonbridge School and Exeter College, Oxford.
Williamson was educated at Tonbridge School and Exeter College, Oxford.
He served in the Royal Signals 1956-1958 as his national service. He began his civil service career in 1958 at the Ministry of Agriculture, Fisheries and Food, becoming Principal Private Secretary to the minister in 1967. He was Deputy Director-General for Agriculture in the European Commission from 1977 to 1983 and Secretary-General of the European Commission from 1987 to 1997.
From 1983 until 1987, Williamson had returned to the United Kingdom to serve as Deputy Secretary and head the European Secretariat in the Cabinet Office.
After leaving Brussels, Williamson was created a Life Peer on 5 February 1999 with the title Baron Williamson of Horton, of Horton in the County of Somerset, and sat as a crossbencher in the House of Lords. Lord Williamson of Horton was the convenor of the crossbenchers, a task that involves keeping the other non-aligned members up-to-date with the business of the House.
He was also sworn of the Privy Council in April 2007.