Baldwin denied he was repeating the same practice: "We're trying to reach people in a straightforward way using existing Facebook tools".
Nicola Sturgeon's message was broadcast from the main stage in Parliament Square.
Others included Dragons' Den businesswoman Deborah Meaden, The Lord of The Ring's actor Andy Serkis, comedian Jenny Eclair, presenter Richard Bacon and TV chef Hugh Fearnley-Whittingstall, who tweeted: "Theresa May is cooking up a Brexit disaster".
Starting at Hyde Park on Saturday (October 20), a horde of people from across the United Kingdom joined the second biggest protest since the one million who attended the Stop the War March in 2003.
He told the BBC that "what's clear is that the only options on the table now from the prime minister are a bad Brexit deal, or no deal whatsoever".
He said, "I was astonished at the sheer number of people marching for a People's Vote, from all age groups, from all over the country and representing all political parties and none".
The last big march on parliament demanding a second vote in June saw an estimated 100,000 gather on and around the picturesque Parliament Square facing Westminster Palace.
He said: "Enfield overwhelmingly voted to stay in the EU and we want to make it clear that Enfield is committed to staying in the European Union". Police did not provide an attendance estimate.
Acknowledging clearly that those calling for a second vote are only doing so out of a desire to stop Brexit from happening altogether, May told the Commons: "Serving our national interest will demand that we hold our nerve through these last stages of the negotiations - the hardest part of all".
The SNP leader said: "Let me say this loudly and clearly, if the issue comes before the House of Commons, SNP MPs will support a People's Vote which includes the option to remain in the European Union". "The People voted to Leave".
As Britain's planned departure in March next year draws closer it faces the prospect of leaving without any agreement, or remaining in a transition phase for several years with few changes but notably losing its decision-making seat at the EU.
Sadiq Khan, the Mayor of London, speaking ahead of his platform appearance, said: "Today will go down as an historic moment in our democracy". In North Yorkshire as a whole a majority of voters voted to leave the European Union, as did Yorkshire as a whole.
'We have just weeks to make our voices heard and have a say on what Britain's future looks like'.
"I'm sure lots of people were".
Mrs May is set to tell MPs that her Brexit deal is 95 per cent done in a Commons statement on Monday following her recent talks with European Union leaders in Brussels.
Many people argue the protest is an affront to the referendum result. "I know what happens when an industry closes - the unemployment, the poverty, the loss of hope, the years it takes to get back on your feet, the grievances that still play out today". "Now we have actual facts and realities of what's going to be happening", he added. "Brexit is not inevitable".