Star Trek actor Sir Patrick Stewart has praised a crowd for "transforming" British politics, after several thousand people took to the streets yesterday to demand a second referendum on Brexit.

He was joined by other celebrities and politicians, including Sandy Toksvig, and Labour's Shadow Cabinet at the People's Vote rally in Parliament Square.

Stewart said the crowd has proved a second referendum was not the "pipe dream" that opponents have described it as.

He said: "You haven't just filled a nice bar in north London, you have taken over an entire city. You haven't just impacted the Brexit debate, you have transformed British politics."

He added there was "nothing democratic" about the 2016 referendum. "People weren't just misled, they were lied to," he said.

Following the Government defeat, four members of Labour's front bench left Parliament to address the rally.

Shadow foreign secretary Emily Thornberry told them: "We must put it back to the people. This is a pivotal moment in our history and it shouldn't be left to a handful of MPs."

READ MORE: Thousands gather for People's Vote March in London

She was joined by shadow Brexit secretary Sir Keir Starmer, who said it was "fantastic" to see the demonstration.

He added: "It's an historic moment, we have defeated Johnson again. We are not going to let him whip out with his sell-out deal.

"We will say no to him again and again. Whatever deal he brings must go back to the people."

On the earlier march, effigies of the Prime Minister had been held aloft by protesters at the demonstration, with some accompanied by their pets draped in EU flags.