LONDON — A giant blimp of a diaper-clad “Trump Baby” and a talking Trump robot sitting on a toilet were among the most vivid props Tuesday as tens of thousands of protesters descended on central London to register their disapproval of President Trump, who was in the British capital for a three-day state visit.

After a day of pomp and pageantry involving the British royals, Tuesday was a day for politics and protests. Trump had meetings at Downing Street, and protesters were hoping that they were close enough — and loud enough — to be heard.

The road outside 10 Downing Street was sealed off with steel barricades, and there was a heavy police presence.

But nearby, the “Carnival of Resistance” was in full swing in on-off rain.

In a news conference Tuesday with outgoing prime minister Theresa May, Trump dismissed the protests. “Even coming over today, there were thousands of people cheering,” he asserted. “A lot of it is fake news, I have to say.”

He added: “I didn’t see the protesters until just a little while ago. And it was a very, very small group of people put in for political reasons. So it was fake news.”

Activists estimated 75,000 people hit the streets Tuesday — fewer than those at the anti-Trump rally in 2018, which organizers said drew more than 100,000.

But the protesters were vocal, their chants — including “Say it loud, say it clear! Donald Trump’s not welcome here!” and “Donald Trump, shame on you!” — ringing in the air as reporters headed to the news conference.

“We come today because we don’t like the tide of right-wing populism that’s going across the Western world, especially in America and Europe,” said Cat Thorneycroft, 35, an illustrator. “I don’t even necessarily mind that he’s had a state visit, but if he’s going to come, then this is what’s going to happen,” she said, referring to the protesters behind her in Parliament Square.

Jeremy Corbyn, leader of the opposition Labour Party, was among those who addressed the crowds. He condemned Trump’s tweets calling London Mayor Sadiq Khan, a longtime Trump foe on Twitter, a “stone cold loser.” Corbyn said he was “proud that our city has a Muslim mayor.”

Trump also denounced Corbyn, calling him a “negative force.”

The Labour leader also said he would resist any attempts to allow private American companies to take over “our precious, wonderful National Health Service. . . . We will not stand for that.”

Trump tweeted Monday that he had not “seen any protests yet, but I’m sure the Fake News will be working hard to find them.” The main protests were planned for Tuesday.

The world’s most famous helium-filled balloon — the 20-foot-tall blimp depicting a baby Trump holding a cellphone — was back, hovering above the scene in Parliament Square. 

Kevin Smith, one of the organizers and “Trump babysitters,” said it was a “very effective way to prick the pomposity and ego of Donald Trump.”

Asked whether it wasn’t a rather juvenile form of protest, he said it was “part of a long tradition in Britain of political caricature. It’s not unlike cartoons in a newspaper — it just so happens to be 3-D and floats in the air.”

During June 4 protests against President Trump's visit to London, a 16-foot-tall, animated "robot" of Trump on a toilet was featured in Trafalgar square. (Press Association)

The organizers of the balloon crowdfunded more than 36,00 pounds ($46,000), which they are giving to groups they describe as “pushing back against the politics of hate and division that are represented by Trump.”

There was also a talking Trump robot that sat on a toilet, saying: “You’re fake news! I’m a very stable genius!” 

The British tradition of creating witty — and sometimes rude — placards was on full display. One protester held aloft a sign that read: “British Humour: the gift of a book to an illiterate man — well played Your Majesty.” As part of a customary gift exchange at the start of the visit, Queen Elizabeth II gave Trump a book by Winston Churchill on World War II. 

Another man was pushing a shopping cart filled with toilet paper featuring Trump’s face on it. “Come on down to Trafalgar and get your Donald Trump toilet paper,” he said.

Footage posted on social media showed supporters and critics clashing at the rally. In one video, a Trump supporter was surrounded by people angrily shouting “Nazi scum!” before he was pelted with a milkshake.

The protests come a day after a lavish state banquet hosted by the queen at Buckingham Palace.

Bryony Doyle, 23, an illustrator and a nanny protesting in Trafalgar Square, said she was “very pleased” that Trump did not “get the red-carpet treatment when he arrived. I know he went for dinner at Buckingham Palace, but he didn’t stay there,” she said. 

The Trumps are staying at Winfield House, the residence of the U.S. ambassador in London, but not Buckingham Palace, which would normally be the case. The palace is reportedly undergoing renovations. 

“I think with us and our culture there’s only so much we can do without feeling impolite,” Doyle said. “I don’t think the queen could actually say no. I think there’s a limit to what the royals can do without causing too much controversy. But that’s not the case with the public, which is why we are here all day!”

Some wondered whether the protests would have any effect.

Mark Davis, 64, a lawyer from California on vacation, said: “Trump could come here and do virtually anything and there are people back in the States who will support him. They’d think he’s being picked on, or this and that. I don’t think this changes anything. In the States, you’re either for him or against him.”

His wife, Monica Richards, 65, a retired employee of Orange County Superior Court in California, said they were nonetheless excited to be among a throng of “like people who have a great hate for Trump. It’s an opportunity to show our support for the forces who are against him.” 

She then unrolled a homemade pink sign that read, “Impeach now.”