Beith became a member of TynedaleDistrict Council in 1973. Later that year, Antony Lambton resigned as an MP following a Fleet Street exposé. At the ensuing by-election on 8 November 1973, Beith was narrowly elected by 57 votes, becoming Berwick's first Liberal MP since 1945.
Just three months after his by-election success, Beith was out canvassing his constituents again at the February 1974 general election, being returned to Parliament with an increased majority of 443. Later that same year and still less than a year after entering the House of Commons, Beith had to contest the constituency for a third time in less than a year at the October 1974 general election, retaining his seat with a slender majority of 73 votes.[6] He held his seat with comfortable majorities in the eight further elections he stood in.
Beith was appointed to the BBC Advisory Council in 1974, and served as a member until 1984. On the election of David Steel as Liberal Leader in 1976, Beith became the Party's Chief Whip in the Commons.[7] After the 1983 general election, he was appointed Liberal Spokesman for Constitutional Affairs. He was elected as Deputy Leader of the Liberal Party in 1985, in both cases continuing his duties as a Commons Chief Whip.
After the 1987 general election, Beith concentrated his efforts as Liberal Spokesman for Treasury Affairs and stood down from being Liberal Chief Whip after eleven years in post. In 1988, the Liberal and Social Democratic parties merged, initially as the Social and Liberal Democrats.
On 19 May 2009, Beith was the first MP to declare his candidacy to succeed SpeakerMichael Martin, who stood down from the position on 21 June 2009. Beith pledged he was "willing to take on the task of leading reform" were he elected as Commons Speaker.[8] Conservative MP John Bercow won, becoming the 157th Speaker of the House Commons of the United Kingdom.[9]
On 22 May 2009, Beith was reported by The Daily Telegraph to have claimed £117,000 in second home allowances while his wife, Baroness Maddock, claimed £60,000 Lords expenses for sharing the same address.[11]
Replying in writing on both their behalf to The Telegraph journalist's exposé: "It would be quite wrong for the taxpayer to pay twice for the same costs, so we have shared the costs, either by sharing the cost of rent, or by my wife using her allowance towards costs incurred (she normally claims only half the Lords' overnight allowance)", he argued in defence.[12]
Coalition Government
At the May 2010 general election he was returned as MP for Berwick; however, his majority was reduced by a substantial swing to the Conservatives.
Beith served as Chairman of the Commons Justice[13] and of the Liaison Select Committees until retiring in 2015.
He was one of only four Liberal Democrat MPs to vote against the third reading of the Marriage (Same Sex Couples) Bill.[14] He was the only Liberal Democrat MP to oppose recognising Palestine as a state in the Commons vote on 13 October 2014.[15][16]
On 7 August 2013, Beith announced that he would retire as an MP at the next election, having at that point represented Berwick-upon-Tweed for 42 years.[18] He was announced as a life peer in the 2015 Dissolution Honours and was created Baron Beith, of Berwick-upon-Tweed in the County of Northumberland on the afternoon of 19 October.[19]
Politics
Beith is more left-leaning and liberal in social issues, and more right-leaning and conservative economically.
Beith was married in 1965 to Barbara Ward, and they had a son and a daughter. His first wife died in 1998, and he then married in 2001 Diana Maddock (née Derbyshire), formerly MP for Christchurch (1993–97).[29]