Star Trek actor Sir Patrick Stewart has praised a crowd for “transforming” British politics, after large numbers of people took to the streets to demand a second referendum on Brexit.

He was joined by other celebrities and politicians, including Sandy Toksvig, and Labour’s shadow cabinet speaking at the People’s Vote rally in Parliament Square.

Sir Patrick said the crowd has proven 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.”

Sir Patrick added there was “nothing democratic” about the 2016 referendum.

“People weren’t just misled, they were lied to,” he said.

Many of the thousands outside the Palace of Westminster cheered as they learned Boris Johnson had lost a key Commons vote on his Withdrawal Agreement, withholding approval of the deal until the legislation to implement it is in place.

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.”

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.”

Brexit
(left to right) Shadow Brexit secretary Sir Keir Starmer, shadow home secretary Diane Abbott, shadow chancellor John McDonnell and shadow foreign secretary Emily Thornberry (PA)

MP Antoinette Sandbach, who had the Conservative whip removed, credited the crowd with “changing her mind” on a second vote.

She said: “My local party voted no confidence in me for resisting no deal.

“It’s undemocratic and not what people voted for, but it’s honourable that I put my job on the line to protect tens of thousands of jobs that will be lost in the north west from no-deal Brexit.”

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.

One group of protesters spotted near Downing Street were pulling a float depicting Number 10 aide Dominic Cummings using Mr Johnson as a puppet.

With “Demonic Cummings” splashed across its forehead, the figure on the float appears to be wearing a Nazi uniform, including an armband which reads Get Brexit Done, and has a Union Jack moustache.

The float was being manned by Phil Jeanes, 67, who said he had driven the sculpture from Dusseldorf in Germany on Thursday night.

Mr Jeanes is part of a group called EU Flag Mafia, and has lived in Essen for the last nine years with his German wife.

Brexit
Protesters pull a float depicting Prime Minister Boris Johnson and Dominic Cummings (Yui Mok/PA)

He said the float had been specifically designed for the People’s Vote march by the German artist Jacques Tilly.

It is the fourth model designed by the artist, who also made a sculpture of Theresa May with her nose impaling a man in a bowler hat.

“He put 14 sketches together and we chose what we thought would be the best,” Mr Jeanes, who is retired, said.

“I suppose we were always intending to do a float for this march and you have to wait and see what is happening at the time.”

Meanwhile, pro-Brexit activists also gathered in Westminster.

Jason Hurt, 48, from Sheffield, was sporting a “I voted Leave” T-shirt, and said he feels people who voted for Brexit are being ignored.

“I voted Leave, I want my voice heard,” he said.

“It is always about the Remainers, never about the Leavers. There are 17.4 million of us, we never get our voices heard.”