Background
Grimston was the son of William Grimston, 1st Viscount Grimston, and Jean Cooke.
Grimston was the son of William Grimston, 1st Viscount Grimston, and Jean Cooke.
He was elected to the House of Commons for Street Albans in 1754, a seat he held until 1761. In 1756 he succeeded his father in the viscountcy but as this was an Irish peerage it did not prohibit him from sitting in the House of Commons. Lord Grimston married Mary Bucknall, daughter of William Bucknall, in 1746.
Lady Grimston died in 1778.