Born in 1853, Sir William Hillier Onslow, Bt. 4th Earl, was educated at Eton and Oxford. He inherited his title in 1874.
He was Lord-in-Waiting to Queen Victoria, Under-secretary of State for the Colonies, Vice-president of the Colonial Conference 1887 and Parliamentary Secretary to the Board of Trade.
He was appointed Governor of New Zealand in 1889 but resigned in 1892 to return to England. He later became President of the Board of Agriculture with Cabinet rank, and then Deputy Speaker of the House of Lords (1906-11). He died in 1911.
Biographical information courtesy of NZ Almanack