A Conservative peer has implored parliamentarians who voted Remain to stay true to their convictions as thousands of anti-Brexit demonstrators marched on Westminster.

A sea of blue and yellow Remainers amassed outside the Houses of Parliament, days after politicians returned to parliament following the summer recess.

It comes as MPs are set to vote on the repeal bill, formally known as the EU (Withdrawal) Bill, on Monday for the first time, amid concerns over the progress of Brexit negotiations.

Addressing the crowds in Parliament Square, Tory peer Baroness Patience Wheatcroft appealed to demonstrators to keep fighting to stay in the EU, telling them: "You have history on your side."

She said that whatever is negotiated "will be worse for Britain" and that Brexit will mean "fewer jobs and a less prosperous Britain".

Protesters make their way along Piccadilly during of a pro-EU People's March For Europe in London.

Appealing to her parliamentary colleagues she said: "We have to stop Brexit. Since we joined the EU we've had an unprecedented period of peace and prosperity. It must be right to try and maintain that.

"It's not undemocratic to try to persuade the electorate to think again about Brexit. That's democracy at work.

"So I say to my colleagues over the road: 'You know in your hearts what's right. Many of you campaigned for Remain, now have the strength of your convictions. Do not be bowed down by the whips. Follow your consciences.'"

Activist and musician Sir Bob Geldof, who had been expected to speak, did not address the crowd and could not be seen at the three-hour rally.

Organisers said there were between 10-15,000 people at the start of the march through central London, estimating around 50,000 protesters at its height as people joined.

The People's March For Europe carries the message "unite, rethink and reject Brexit" and organisers said leaving the EU "no longer holds credibility inside Westminster, let alone on the streets of Britain".

EU flags were out in force, as were Exit From Brexit placards, while T-shirts with the words Remoaner Till I Die and Je Suis Un Saboteur could be seen.

Former cabinet minister Sir Ed Davey told the crowd he was "embarrassed" for Great Britain.

I've gone from anger to distress, from fury to despair

Liberal Democrat MP for Kingston and Surbiton said: "I've gone from anger to distress, from fury to despair. But since the Brexit negotiations began there's a third emotion I've been feeling.

"Embarrassment. Embarrassment at our country's leaders. Embarrassment for Great Britain."

After being interrupted by boos, he said he felt embarrassed "that these shambolic people are supposed to be representing us. They can't even negotiate."

He personally thanked Conservative and Labour Remainers who voted for him to be their MP, so he could continue to oppose Brexit.

Jean Lambert, member of the European Parliament (MEP) for London, said she wanted a "meaningful vote" for people across the UK following the Brexit negotiations.

The Green Party member said: "Even basic consumer protection says you have a cooling-off period, a time to consider whether or not you are being offered what fits your needs and your ambition.

"So (I want) a vote for the people, not just the politicians."

The blue and yellow demonstrators observed a minute's silence in respect for the victims of the Grenfell Tower fire, breaking into applause as the 60 seconds ended.

They were led in the reflection by a Sikh leader local to the North Kensington community, Bhupinder Singh, who said the Brexit vote had led to an "us and them" society, a bigger rich-poor divide and an increase in racism.

Recalling how the local community came together after Grenfell, and urging the crowd against division, he said: "The word community contains unity and that should be your catchphrase as well. That united we are strong."