Thousands of protesters took to the streets calling for Brexit to be ditched as the Tories gathered for their autumn conference.
Campaigners marched through Birmingham on Sunday waving anti-Brexit banners before holding a huge two-hour rally in the city centre.
Tim Skeet, from the group Tories against Brexit, told the crowd: "A certain prime minister is continuing to drive this bus over the cliff.
"The only way forward is to bin Brexit and to remain in the EU."
Anti-Brexit protest Birmingham
Labour peer Lord Adonis mocked the Conservatives for the security issues they suffered with a party app as the conference opened.
"These are the people who tell us they can have the IT systems in place and all of the technology for Canada plus plus, for the frictionless border, for free trade without borders in Ireland," he added.
"It is a complete farce. There isn't such a thing as a good Brexit," he added.
Philosopher AC Grayling said he was optimistic a fresh vote would be held.
"We are going to keep on fighting," he told the Best for Britain rally. "We are not going to give up."
Andrew Hardie, 46, a language teacher from Bristol, voted Leave but has since changed his mind.
He said once the referendum result was known he thought, "What the heck have I done?"
"In a way, me turning up today is almost me trying to make some sort of recompense for the mistake I made at the ballot box," he said.
Also on Sunday an opposing Leave Means Leave rally took place in Solihull.
Former Ukip leader Nigel Farage told the rally politicians must be made to "feel the heat" if they were about to betray the decision made in the 2016 referendum.
"This is now about a matter of trust between us - the people - and our political class," he said.
"They are trying to betray Brexit and we are here today to tell them 'we won't let you get away with doing that'."
In a message to the enthusiastic crowd he added: "I want you to make our political class, who are on the verge of betraying Brexit, feel the heat.
"We are mobilising the people's army of this country that gave us victory in Brexit and will never rest until we have become an independent, self-governing, proud United Kingdom."
Tory MP Peter Bone said: "I will stand up for Brexit but we need to chuck Chequers."
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Setting out his opposition to the European Union, he said: "We didn't fight world wars to be subservient. We want to make our own laws in our own country."
He dismissed suggestions that public opinion had changed since the 2016 vote, saying: "The idea that the British people have changed their minds and want to remain is completely untrue."
Additional reporting by Press Association
