Brexiteers banged on a drums and rang a "liberty" bell while pro-Europeans bellowed "Stop Brexit! and handed out "Bollocks to Brexit" stickers.
"It's about getting the message out across Britain: 'stand up, people, we don't have to accept this!' said Bray, 49, donning a half EU, half UK flag on his back.
As the debate over Brexit has intensified inside the hallowed halls of Westminster, the scene on the streets outside has become more charged as well.
At times, it has turned ugly. Last week, a group of far-right protesters shouted "Soubry is a Nazi" at the pro-European Conservative MP Anna Soubry and later swarmed her when she tried to enter Parliament.
Generally, though, protesters say the scene is good-natured, if emotionally charged.
Walking through the thick crowds today, you could pick up snippets of conversations like "you're a traitor" and "why do you assume I'm a racist?" But there was also laughter and cheering, too.
Placards ranged from "The best deal is with the EU" to "No Deal? No problem" to "Treason May." There was also a lot of honking, with both sides holding aloft placards encouraging drivers to vote with their horns as they drove past.
As Brexit has grown more uncertain over the past few weeks - no one really knows what's going to happen if/when May loses the big Brexit vote - protesters on both sides have started to pour onto the streets.
"The deal is a betrayal," said Penelope Becker, 61, who was carrying a sign that said "leave means leave".
"It's worse than a divorce deal. If you get divorced, you don't leave to a later date to decide who's going to do the day-to-day care of the kids," she said.
"We voted 2.5 years ago in a democratic referendum, we won the majority," she added, "but at the moment, it's looking like the great betrayal."
May has tried to pitch her deal as the least worst-option, but many Brexiteers don't buy the compromises she says are needed.
They say they don't like May's deal because, they think Britain will be yoked to the EU for years, maybe forever. They'd prefer a different deal, or even to leave the bloc with no deal at all, the default legal position if nothing else is agreed on between now and the end of March.
Robert Wright, a 64-year-old retired accountant, started protesting outside Westminster in December when, he said, "it became clear that Theresa May deceived us".
"No country has ever signed a deal that they couldn't get out of," he said, adding that "we have nothing to fear from World Trade Organisation rules".
Despite his side winning the Brexit vote 52 per cent to 48 per cent, he's not confident that Brexit will happen at all. "Trust in our government and our Parliament is at a very very low level," he said.
Others oppose May's deal for different reasons.
"Cutting ourselves off from our European neighbours is such a backwards step," said Matt Hence, 41, a transport manager who was wearing a hat with a sticker that said "Bollocks to Brexit". He said he believes in "European values," and thinks that Brexit will translate into higher food prices.
Of all the protesters outside Westminster, Bray, a rare coin dealer from Wales, is the best known.
Upset by the Brexit vote, he began his daily protests 17 months ago.
He's become skilled at appearing in broadcast footage, either by shouting "stop Brexit" so loudly it's impossible not to hear him, or by simply popping into the frame when broadcasters are filming live from the lawn outside of Parliament. He's determined, too: When broadcasters erect platforms, he finds a larger flagpole.
Last week he clocked 60 hours outside Parliament. He lives with a friend in London, rent-free, and raises money from selling pro-EU merchandise.
He said he is more optimistic about Brexit not happening than ever before.
"She's not going to get that deal through Parliament, hell will freeze over," he said. "We're not going to be leaving the European Union anytime soon - or at all."
And then he turned toward Parliament and shouted: "Stop Brexit!"
