Organisers said about 1200 people were at the event, including MPs from all leading parties.
According to the BBC, the idea of the campaign is to unite anti-Brexit movements.
The People's Vote campaign is spearheaded by United Kingdom lawmakers of various parties, as well as celebrities and business leaders, British media report.
The rally at the Electric Ballroom attracted support from the Conservatives' Anna Soubry, Labour's Chuka Umuna, Liberal Democrat's Layla Moran and the Green Party's only MP Caroline Lucas.
Sir Patrick told Sky News there is "no doubt" both Star Trek's Jean-Luc Picard and X-Men's Professor Charles Xavier would have backed staying in the European Union. And why? Because unity, common cause, wellbeing of society and debate were paramount to belief of this fictional character.
Meanwhile, pro-Brexit demonstrators also turned up at the launch, and Conservative MP Nadine Dorries argued there was no public appetite for a second referendum.
"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 I support a people's vote on the final deal".
"These people just want to keep re-running the referendum until they get the answer they want".
Trump lawyer arranged $1.6 mln payoff to Playboy Playmate for Republican fundraiser
Davidson and Cohen were also in communication about a third agreement involving former Playboy centerfold Karen McDougal . Those are the same names used to identify Donald Trump and Daniels (real name Stephanie Clifford ) in a 2016 agreement.
"We will be making the case in Parliament, but this is too big and too important to be determined exclusively by politicians", she said.
"The way I see it is this: as Brexit unfolds and people see the reality of it, for the first time ever I think in any country's history we have actually had a government that has said to its people that we are about to embark on a course that - which ever way you cut it, whatever deals comes out - you and your grandchildren will be less prosperous than you are now".
"They are elitists who think they know best and don't want to respect the will of the British people".
"We'll do everything we can in Parliament for a people's vote. The public don't want it".
Actor Patrick Stewart, a supporter of the People's Vote campaign, said campaigners were not asking for a second referendum, but rather wanted "another chance to consider what the terms of this divorce are going to be".
"People had a vote, it was a great vote, and they voted with a substantial majority to leave the European Union", he told the BBC.
"I think we'll get a great result and we'll be able to have, not only a very big free trade deal with our friends and partners across the Channel, but we'll be able to boldly go to areas we perhaps neglected over the past five years". "We're now trying to deliver on that mandate from the people".