LONDON -- A new campaign group, backed by a star from the Star Trek movies, was launched Sunday calling for a public vote on a final Brexit deal.

The People's Vote campaign, which held its launch event in Camden, London, is backed by high-profile MPs from the major political parties, business leaders and celebrities, including the British star, Sir Patrick Stewart, who played Captin Jean-Luc Picard in Star Trek: The Next Generation.

Britain is due to end its membership of the European Union next March, with both the governing Conservatives and main opposition Labour parties rejecting calls for a second referendum.

In the first referendum in June 2016, Britain voted by a 52-48 margin to leave the EU.

Nine grassroots anti-Brexit groups have joined forces in the new campaign which is demanding a public final say on the eventual Brexit deal Prime Minister Theresa May reached with Brussels.

The campaign brings together Open Britain along with the European Movement and another seven organisations that collectively claim to have more than 700,000 supporters, 20,000 activists, and more than a million followers on social media.

James McGrory, executive director of Open Britain, which is supporting the People's Vote campaign, said: "Whether you think the government will negotiate a good deal or bad deal, Brexit is definitely a big deal."

"Brexit is not inevitable. What the government comes back with, not what was promised in the referendum, will be the real deal. It should not be a done deal."

"Brexit will affect everybody in the country, which is why it should not be left to 650 politicians to decide our future but 65 million people. That is why so many are demanding a People's Vote on the final Brexit deal."

The British parliament's only Green MP, Caroline Lucas, said: "This is too big and too important to be determined solely by politicians. If the public demand a People's Vote, politicians will fall in line."

Liberal Democrat MP Layla Moran, a leading supporter of the People's Vote campaign, said:"It may seem like the odds are stacked against us as a movement, but fighting for what you believe in is never easy. We are short on time, but we have people power on our side. Together, are on the verge of something extraordinary."

Actor Stewart said in a media interview Sunday that if people voted to reject the exit deal, Britain would simply stay in the EU.

He said the group does not oppose the result of the 2016 EU referendum or call for a second referendum.

Stewart added: "As time has gone by, the information that we are receiving about the terms and conditions of that separation are quite unlike the terms and conditions that were spoken of so loosely during the 2016 campaign."

Foreign Secretary Boris Johnson, responding to the new campaign, said the people's vote had already taken place, adding: "They voted with a substantial majority to leave the EU. We're now trying to deliver on that mandate from the people."