Background
Onslow was the son of William Onslow, 4th Earl of Onslow and the Honourable Florence Coulston Gardner.
Onslow was the son of William Onslow, 4th Earl of Onslow and the Honourable Florence Coulston Gardner.
He was educated at Eton and New College, Oxford before joining the Diplomatic Service in 1901.
He became an Attaché to Madrid a year later, Third Secretary to Tangier in 1903 and to Street St. Petersburg in 1904 and Second Secretary to Berlin in 1907. In 1909, he became assistant private secretary to Sir Edward Grey, the Secretary of State for Foreign Affairs. He then held a number of positions in the Foreign Office as a clerk in 1910, private secretary to the Under-Secretary of State for Foreign Affairs from 1911-1913 and assistant clerk from 1913-1914.
In later years he was Honorary Lieutenant-Colonel of the 3rd Battalion Queen"s Royal Regiment (West Surrey) and Honorary Colonel of the 30th (Surrey) Searchlight Regiment, Royal Artillery.
Onslow had succeeded to his father"s title and seat in the House of Lords in 1911. After the war, he was a Lord-in-Waiting from 1919 to 1920, a Civil Lord of the Admiralty from 1920 to 1921, Parliamentary Secretary to the Ministry of Agriculture and Fisheries in 1921, Parliamentary Secretary to the Ministry of Health from 1921 to 1923, Parliamentary Secretary to the Board of Education from 1923 to 1924, Under-Secretary of State for War and Vice-President of the Army Council from 1924 to 192828 and Chairman of the Committees and Deputy Speaker of the House of Lords from 1931-1944.
Onslow was also President of the Royal Statistical Society from 1905 to 1906 and President of the Zoological Society of London from 1936 to 1942. Lord Onslow married the Honourable Violet Marcia Catherine Warwick Bampfylde, the only daughter of Coplestone Bampfylde, 3rd Baron Poltimore, on 22 February 1906.
They had two children: Lady Mary Florence Violet Margaret Onslow William Arthur Bampfylde Onslow, 6th Earl of Onslow (born 11 June 1913, died 3 June 1971) As Dowager Countess of Onslow, Violet gave the future Queen Elizabeth II a diamond and ruby butterfly brooch as a wedding gift in 1947.
She died on 23 October 1954.