Lord Grenfell first entered the House of Lords in 1976, and was then created a life peer as Baron Grenfell of Kilvey, of Kilvey in the County of Swansea in 2000.
Since 2002 he has served as both Principal Deputy Chairman of Committees and Deputy Speaker.
Since 2002, Lord Grenfell has been Chair of the European Union Select Committee, and since 2000 he has been Chair of the European Union Sub-Committee A (Economic and Financial Affairs, Trade and External Relations). He was also a Member of the Procedure Committee from 2003 to 2007.
From 1997 to 1999 Lord Grenfell was a member of the UK Delegation to Parliamentary Assemblies of Council of Europe and Western European Union. He has been Secretary of the Croatia All-Party Parliamentary Group since 2002, and the Belgium All-Party Parliamentary Group since 2006.