Archibald Sinclair was born on 22 October 1890, only son of Clarence Granville Sinclair, the eldest son of Sir Tollemache Sinclair, and Mabel Sands. He was educated at Eton and Sandhurst, and succeeded his grandfather in 1912 (his father, Clarence Sinclair, having died in 1895) and married Marigold Forbes in 1918, having two sons and two daughters.
Sinclair entered the army in 1910 in the 2nd Life Guards. In February 1915 he was appointed aide-de-camp to John Seely [later 1st Lord Mottistone], commander of the Canadian cavalry brigade, then from January 1916 served for four months as second in command to his friend Winston Churchill, with the 6th Royal Scots Fusiliers, ending the war as a major in the Guards Machine-Gun regiment.
After the war Sinclair returned to Churchill, now Secretary of State for War, serving as his Personal Military Secretary, 1919-21, then as his Private Secretary when Churchill became Secretary of State for the Colonies, 1921-22. Sinclair then entered politics on his own account, becoming Liberal MP for Caithness and Sutherland in 1922, a seat which he was to hold until 1945. He served as Temporary Chairman of Committees in the House of Commons, 1925-30, was a member of the Empire Marketing Board, 1927-30 and became Chief Liberal Whip, from 1930-31, before becoming Secretary of State for Scotland, 1931-32. Sinclair then became Leader of the Liberal Parliamentary Party, 1935-45, then during the war once again served under Churchill, as Secretary of State for Air, 1940-45.
Sinclair lost his seat in the 1945 election, and after standing unsuccessfully for Parliament again in 1950, he was created Viscount Thurso of Ulbster in 1952. He was President of the Air League of the British Empire, 1956-58 and served on the Political Honours Scrutiny Committee, 1954-61.
Sinclair was appointed CMG in 1922, knighted in 1941, and was made a privy councillor in 1931. He died on 15 June 1970.
The collection held at Churchill Archives Centre includes correspondence (including general, official, political, constituency, parliamentary and family correspondence); speeches; Liberal Organisation and Scottish Liberal organisation and Federation material; press cuttings; business papers; and Scottish Office, Scottish Board of Health and Secretary of State for Scotland material.
For the most part, the collection is made up of constituency, parliamentary and Liberal party correspondence of the 1920s and 1930s. There is very little wartime material but Section IV contains correspondence (arranged alphabetically by correspondents' names) and press cuttings from 1945 on into the 1950s. The papers transferred from the Scottish Record Office form a separate and coherent group, consisting of papers of 1923-1937 relating to the Scottish Office, the Scottish Board of Health and Thurso's period as Secretary of State for Scotland. The papers in the first box of Section I are also particularly noteworthy as they include Thurso's correspondence with Winston Churchill from 1915 to 1920.
The papers of Archibald Sinclair, 1st Viscount Thurso, came into Churchill Archives Centre through the good offices of his son, the 2nd Viscount, in several batches between April 1972 and September 1973. The material in THRS VIII was lent by the family to Lord Thurso's biographer, Professor Gerard De Groot, and was deposited by De Groot to join the rest of the papers at Churchill Archives Centre in March 2010.
The collection had incurred two major misfortunes before its transfer to Cambridge. During the war, the bulk of the Thurso papers that were being stored in Liberal Party headquarters in London were destroyed by an incendiary bomb. After the war, a large portion of the remaining papers were destroyed in a fire that broke out at Thurso East Mains where they were being kept in a room above the laundry. Most of the papers that were rescued from this second blaze were severely damaged both by the flames and by water from the firemen's hoses. Section VI of the collection contains the charred remains of this accident which are too fragile to handle whilst those damaged files which have already been repaired by the Conservator have been placed in their appropriate places within the collection.
In Viscount Thurso's own lifetime, he was asked by the Scottish Record Office (in 1966) if he would deposit there the papers relating to his tenure of the office of Secretary of State and these papers were consequently deposited in Edinburgh early in 1972. At the same time, Viscount Thurso's son began the transfer of the residue of his late father's papers (the 1st Viscount had died in June 1970) to Churchill College. These papers are our Sections I and II.
In January 1973 the Scottish Record Office agreed to transfer their Thurso papers, relating to his time as Secretary of State for Scotland, to Churchill College, having first xeroxed them. This collection was catalogued in the National Register of Archives (Scotland) Survey 189 (Additional) and comprises Section V of our Thurso collection.
By the spring of 1973, Viscount Thurso's secretary, Miss Cynthia Metcalf, was sorting and listing the papers that were to be deposited here in May and September that year as Sections III and IV. As Section VIII (the family correspondence and business papers) came in much later than the rest of the archive (in 2010) and consisted of different material to anything else in the archive, it was given its own section rather than add it to any existing series.
Within each series, the papers were numbered by box, so instead of the normal running file numbers, the papers are numbered by files within individual numbered boxes.