Lieutenant-Colonel Robert George Grosvenor, 5th Duke of Westminster, TD, JP, DL (24 April 1910 – 19 February 1979) was a British soldier, landowner, businessman and politician. In the 1970s he was the richest man in Britain.
Grosvenor was born Mr. Robert Grosvenor, younger son of Lord Hugh Grosvenor, himself the sixth son and tenth child of Hugh Grosvenor, 1st Duke of Westminster by his second wife, the Hon. Katherine Cavendish, daughter of William Cavendish, 2nd Baron Chesham. Grosvenor's mother, Lady Mabel Crichton, was the daughter of John Crichton, 4th Earl Erne.
Grosvenor was educated at Eton College, an all-boys public boarding school in Berkshire. He was a member of the school's contingent of the junior division of the Officer Training Corps. He reached the rank of cadet lance corporal.
On 28 June 1938, Grosvenor was commissioned into the 11th (City of London Yeomanry) Light Anti-Aircraft Brigade, a newly formed Territorial Army unit of the Royal Artillery, as a second lieutenant. He ended World War II as a war substantive major.
On 1 May 1947, he transferred to the reformed City of London Yeomanry (Rough Riders) and was promoted from his pre-war substantive rank of second lieutenant to major with seniority from 24 April 1944. His service number was 76151. He transferred to the North Irish Horse on 1 May 1949. On 11 November 1949, he was awarded the Efficiency Decoration (TD) for long service with the Territorial Army. He was promoted to lieutenant colonel on 15 February 1953. He was awarded a clasp to his Efficiency Decoration on 26 October 1954. On 14 February 1956, he moved from the Active List to the Territorial Army Reserve of Officers. He resigned his commission on 15 April 1960 and was permitted to retain the rank of lieutenant colonel.
See Colonel The 5th Duke of Westminster, TD, DL