William David Trimble (born 15 October 1944) is a former leader of the Ulster Unionist Party, First Minister of Northern Ireland and MP for Upper Bann. He was appointed a Conservative peer in the House of Lords as Lord Trimble of Lisnagarvey.  He is a trustee of the neoconservative think-tank the Henry Jackson Society.  He is one of the Founder Members of the neoconservative Israel lobby group The Friends of Israel Initiative,  the UK launch of which was hosted by the Henry Jackson Society.
- O'Callaghan used to advise David Trimble on IRA thinking which Trimble took, together with snippets of intelligence leaked to him by the RUC, to build up a picture of republican intentions, often completely wrong, but sometimes better informed than us, or at least more up to date since the police information seemed to get to him first. On the basis of this information, Trimble was convinced that Sinn Fein would not be able to meet the tests that were being imposed on them in 1997, and that therefore he would not face the difficult dilemma of whether or not to go into government with them. 
- Friends of Israel Initiative
- Henry Jackson Society Project for Democratic Geopolitics
- Conservative Party
- Ulster Unionist Party
- David Trimble joins the Conservatives, Conservative Party, 17 April 2007.
- Charity Commission, The Henry Jackson Society for Democratic Geopolitics > Contact and trustees [Accessed 8 September 2010]
- PDF Copy of The Friends of Israel Initiative > About > Founder Members <http://www.friendsofisraelinitiative.org/about-advisors.php> created 15 July 2010.
- Great Hatred, Little Room, Making Peace in Northern Ireland, by Jonathan Powell, The Bodley Head, London, 2008, p19.