He was educated at Eton and Trinity Hall, Cambridge.
He succeeded his father in the viscountcy in 1773 but as this was an Irish peerage it did not entitle him to a seat in the House of Lords. He was instead elected to the House of Commons for Street Albans in 1783, a seat he held until the next year"s election, where he instead stood for and represented the larger, county level seat of Hertfordshire from 1784 to 1790. In 1790 he was created Baron Verulam, of Gorhambury in the County of Hertford, in the Peerage of Great Britain, which gave him a seat in the House of Lords.
Lord Grimston married Harriot Walter, daughter of Edward Walter of Bury Hill, Westcott, Surrey and Harriot Forrester, daughter of George Forrester, 5th Lord Forrester.
Royal Society; 15th Parliament of Great Britain. 16th Parliament of Great Britain.