Veteran gay rights campaigner Peter Tatchell is to stand as a Green Party candidate at the next general election.
Peter Tatchell is active in gay rights campaigning
Mr Tatchell, who as a Labour candidate in 1983 fought the infamous Bermondsey by-election, will contest Oxford East, which is held by Labour's Andrew Smith.
The man who once tried to arrest Robert Mugabe promised "the same determination to fight hard for Oxford East".
Green Party principal speaker Derek Wall said: "He is going to raise the game for the whole party."
He added: "I think his selection will be seen as a real turning point, making the party more serious, more professional and more focused on issues of justice."
The Green Party has never had anyone elected to the House of Commons, but has one peer in the House of Lords and two European Parliament Members.
Mr Tatchell said: "The people of Oxford have an opportunity to make history by electing Britain's first Green MP."
He added: "I plan to start living part-time in the constituency and to get immersed in local community campaigns."
He warned that he would not be "bossed around by the party whips" but be an "independent-minded" Green MP.
Mr Tatchell, who has supported the Green Party since 1988, contested the Bermondsey by-election in 1983 for Labour.
He lost to Liberal Simon Hughes in a bitter battle in which there were accusations of homophobia, after the Liberals used the term a "straight choice".
At the last General Election in Oxford East Labour won with 36.9% of the vote, the Lib Dems were second on 34.6% with the Conservatives getting 16.7% and the Greens in fourth place on 4.3%.