As leader of the non-sectarian Alliance Party, Lord Alderdice must deal with a challenge faced by all his predecessors - how to retain the support of voters from both sides of the community.

While he produced the party's best-ever showing in a contest for a Westminster seat, he was never elected as an MP and was later given a peerage.

He became leader of the Alliance Party in 1987 at the age of 32. The son of a Presbyterian minister, he is a consultant psychiatrist.

Many of the central elements of the Good Friday Agreement, such as a local assembly with shared responsibility between the two communities, have been Alliance policy for years.

Lord Alderdice has argued that such a deal contains all the necessary compromises to ensure the majority of people in Ireland, north and south, can support the deal.

He has repeatedly warned that young people were being alienated from the political process in Northern Ireland by politicians who continued to maintain the attitude of "not an inch".

But having achieved much of what his party wanted in a compromise deal, Lord Alderdice must now address fundamental questions about where the party goes from here.

In his professional capacity he has said that psychiatrists in Northern Ireland were seeing people in their 20s and 30s who could not suppress the horrors of growing up through the violence of the early years of the troubles.

At Westminster he has developed a close working relationship with the Liberal Democrats, and with the Progressive Democrats in the Irish Republic.