British Conservative politician and statesman, eldest son and heir of James Edward Hubert Gascoyne-Cecil, 4th Marquess of Salisbury. Educated at Eton and Christ Church, Oxford, he served with the Grenadier Guards during the First World War and was awarded the Croix de Guerre. He entered the House of Commons for South Dorset in 1929 and later became one of the principal Conservative leaders in the House of Lords. As Viscount Cranborne he was elected to the Order of the Garter in December 1946; on his father's death at Hatfield on 4 April 1947 he succeeded as 5th Marquess of Salisbury. He played a central role in the post-1945 negotiations between the Labour government and the Conservative opposition concerning the powers and conduct of the House of Lords, and held several senior offices in the Churchill, Eden and Macmillan governments.

Hansard person record for Viscount Cranborne — https://api.parliament.uk/historic-hansard/people/viscount-cranborne-1/index.html
The National Archives, Historical Manuscripts Commission, 28th Report — https://cdn.nationalarchives.gov.uk/documents/information-management/archmill.pdf
The Peerage, Robert Arthur James Gascoyne-Cecil, 5th Marquess of Salisbury — https://ftp.thepeerage.com/p1103.htm
The Peerage biographical exhibit — https://www.thepeerage.com/e630.htm
Order of the Garter appointments list — https://www.themcs.org/Documentation/Information/Members%20of%20the%20Order%20of%20the%20Garter%2C%201348-present.pdf
Wikimedia Commons raster depiction of the Viscount Cranborne stall-plate arms — https://commons.wikimedia.org/wiki/File:Coat_of_Arms_of_Robert_Gascoyne-Cecil,_Viscount_Cranborne,_KG.png
Wikimedia Commons raster depiction of the later 5th Marquess's achievement — https://commons.wikimedia.org/wiki/File:Coat_of_arms_of_Robert_Gascoyne-Cecil,_5th_Marquess_of_Salisbury,_KG,_PC,_DL,_FRS.png
National Portrait Gallery authority record — https://www.npg.org.uk/collections/search/person/mp63175/robert-arthur-james-gascoyne-cecil-5th-marquess-of-salisbury