 In 1981, Wrigglesworth became one of the founding members of the SDP and with Mike Thomas organised the launch of the new party in March 1981.Wrigglesworth was one of only six SDP Members of Parliament to be returned to the House of Commons in the 1983 general election when he narrowly won the newly created constituency of Stockton South by 102 votes.In the 1987 general election, he was narrowly defeated by the Conservative candidate, Tim Devlin, by 774 votes.