East Grinstead was a parliamentary constituency in the Kingdom of England, the Kingdom of Great Britain, and the United Kingdom. It first existed as a Parliamentary borough from 1307, returning two Members of Parliament to the House of Commons elected by the bloc vote system. The borough was disfranchised under the Reform Act 1832, but the name was revived at the 1885 election when the Redistribution of Seats Act created a new single-member county division of the same name.

Thomas Sackville, 1st Earl of Dorset was an English statesman, poet, and dramatist. He was the son of Richard Sackville, a cousin to Anne Boleyn. He was a Member of Parliament and Lord High Treasurer.