Williams attended Sandfields Comprehensive School, Baglan, in Port Talbot.

From 1999 to 2005, Williams was the Special Adviser to two UK Foreign Secretaries, Robin Cook (1999–2001) and Jack Straw (2001–2005).

He was a member of the Executive Committee and Council of Chatham House (Royal Institute for International Affairs).

[5] He had served as Chair of the Trustee Board of the British humanitarian demining charity MAG (Mines Advisory Group) since 2013.

He was created Baron Williams of Baglan, of Neath Port Talbot in Glamorgan, on 23 July 2010[7] and, on being introduced into the House of Lords, took his seat on the Labour benches.