Ashdown was born in New Delhi in India, where his father was a colonial administrator, but was brought up in Northern Ireland. From 1959 to 1972 he served in the Royal Marines as an officer in the commandos and the Special Boat Service. After leaving the Marines he worked for the Foreign Office, in industry and as a youth worker before being elected Liberal Member of Parliament for Yeovil in 1983.
In the Commons, he was SDP-Liberal Alliance spokesman on Trade and Industry and then on Education. After the merger that formed the Liberal Democrats, he was elected as the new party's leader. He led the Liberal Democrats in two general elections, in 1992 and 1997.
As leader, he was a notable proponent of co-operation between the Liberal Democrats and the "New" Labour Party, and had regular secret meetings with Tony Blair to plan a coalition government. After Labour's 1997 victory, a "joint Cabinet committee" was established, and the Jenkins Commission, with Roy Jenkins as its chair, was formed to consider electoral reform, Ashdown's key demand. The plan to bring Liberal Democrats into the government continued, according to Ashdown's published diaries, but foundered on opposition from senior Labour ministers.
He resigned the leadership in 1999, being succeeded by Charles Kennedy. He was knighted in 2000 and became a life peer in the House of Lords after retiring from the House of Commons in 2001. A long-time advocate of international intervention in Bosnia and Herzegovina, he took up the post of High Representative on May 27, 2002.
Paddy Ashdown is married with two children and two grandchildren. The nickname "Paddy Pantsdown" was given to him by The Sun in 1992, when it was revealed that he had had an affair. He is a gifted linguist, and is fluent in Mandarin Chinese and other languages.