Sir William Patey – British Ambassador to Kabul, 2010-2012 (Retired)

Has western military intervention in Afghanistan failed?

The question will hang over this weekend's Nato summit in Chicago as the alliance's political leaders set the seal on a phased military retreat while pledging long-term support for the Afghan Government.

Stephen Sackur speaks to Sir William Patey who has just retired from his post as British ambassador in Kabul.

Did the West get the balance between war and diplomacy fundamentally wrong in Afghanistan?