Thomson, George Reid (1893–1962), lord justice clerk, was born in Glasgow 11 June 1893, the eldest of the four children of the Revd William Rankin Thomson, of the United Presbyterian Church of Scotland, and his wife, Agnes Macfee. The Revd W. R. Thomson spent much of his life as a clergyman in South Africa, and G. R. Thomson received his early education at the South African College, Cape Town. He went up to Corpus Christi College, Oxford, as a Rhodes scholar in October 1911 and obtained a second class in classical honour moderations in 1913. Like many of his contemporaries, he abandoned Oxford at the outbreak of war in 1914. He joined the Royal Fusiliers as a private soldier, was commissioned in the 5th Argyll and Sutherland Highlanders in 1915, and served in Egypt, Palestine, and France. He was wounded in action, promoted captain, and mentioned in dispatches. On demobilization he did not return to Oxford but took his degree in 1920 under the decree which exempted those who had served in the armed forces from further examination. He was elected an honorary fellow of Corpus in 1957.

He entered the law faculty of Edinburgh University in 1919, and graduated bachelor of laws with distinction in March 1922, after having been awarded the Muirhead prize, the Dalgety prize, the Thow scholarship, and the Vans Dunlop scholarship, which he shared with John (Lord) Cameron. He was given the degree of honorary doctor of laws by Edinburgh University in 1957.

He was admitted advocate 1922. He had no legal connections and was an unspectacular pleader and it was some time before solicitors appreciated the virtue of his firm grasp of legal principles, his thorough preparation of even the most trivial case, and his sound common sense. He gradually built up a substantial practice in cases under the Workmen's Compensation Acts and similar fields, but it was not until 1936, when he took silk, that his talent for synthesis and his ability to reduce a complex argument to a few and concisely stated propositions emerged. It was quickly recognized and he acquired a large and broadly based practice. He was an advocate depute from 1940 to 1945.

On the formation of the Labour Government in 1945 he was appointed lord advocate and a member of the Privy Council. The Government had a large legislative programme and the prime minister, Attlee, wished to have his assistance in the Commons. Against his better judgement, Thomson was persuaded to stand for East Edinburgh, where a vacancy was created for him by the elevation of F. W. Pethick-Lawrence [q.v.] , the sitting member, to the peerage. Thomson was elected by a substantial majority. His commitment to the Labour Party resulted from his sympathy with the underprivileged, and his approach to political problems was pragmatic and not ideological. This approach, his dislike of rhetoric, and, above all, his contempt for what he called ‘the ya-boo’ of party strife, and the heated atmosphere of a House of Commons, largely concerned with bitterly fought nationalization legislation, made this an unhappy period in an otherwise happy life.

In March 1947 the office of lord justice clerk fell vacant. Thomson wished for the appointment, but the prime minister felt unable to do without him in the Commons, and Lord (Alexander) Moncrieff was appointed. This was clearly a stop-gap appointment, and when Lord Moncrieff resigned in October 1947, Thomson was appointed lord justice clerk. He presided over the Second Division of the Court of Session and the Court of Criminal Appeal, and, from time to time, sat as a judge of first instance. He was a patient and attentive judge, courteous to all, rarely interrupting a witness or counsel, and then only in a search for clarification. He desired the truth, but he was very conscious of the limitations of the legal process and, as he put it in an often quoted judgement, ‘A litigation is in essence a trial of skill between opposing parties conducted under recognized rules, and the prize is the judge's decision’. His judgements were based on the application of broad legal principles to the ascertained facts, and were couched in simple and sometimes racy language, which reflected his knowledge of human affairs and wide reading. He is said to have quoted Homer in the original Greek in the course of a hearing before him.

His real genius lay in his sincerity, simplicity, and friendliness. In 1925 he married Grace (died 1980), daughter of the Revd Daniel Georgeson, of Bowling. They had no children. They had a most happy marriage and created in their home a centre of hospitality for a wide circle of friends. Every young advocate—and his bride, when acquired—was bidden to and made most welcome at their home, not as a duty imposed by his office, but because they both liked young people and lively minds. He was a discerning collector of modern Scottish paintings, a fisher, and an enthusiastic and skilful golfer, who delighted to select, organize, and captain the Scottish team in the annual match against the English bench and bar.

He was taken ill while on holiday in Spain and died 15 April 1962 at Gibraltar.