The pomp and circumstance of President Trump’s three-day state visit to the UK turned into protests as he met with outgoing Prime Minister Theresa May.

Thousands of demonstrators flooded the streets of London, bringing traffic to a standstill as they waved signs that said “Dump Trump” and “Liar” and chanting, “Donald Trump’s not welcome here.”

The 20-foot-tall blimp known as the “Trump Baby” also flew overhead.

Crowds assembled in Trafalgar Square and streamed toward the Houses of Parliament — around the corner from 10 Downing Street, where May and Trump were meeting to discuss trade and other matters.

The night before, protesters trolled Trump by flashing an enormous image of the USS John S. McCain, as well as UK approval ratings for him and former President Barack Obama.

Top officials in the UK were also incensed at Trump’s presence.

“A state visit is an honor, and we don’t think that this president deserves an honor,” UK Shadow Foreign Secretary Emily Thornberry said on BBC’s “Today” radio show Tuesday. “He is a sexual predator, he is a racist, and it’s right to say that. And I think we need to think about when is it that our country got so scared. Why can’t we start saying things as they are?”

She added, “We’ve seen the way in which this current British government have tried to deal with Donald Trump, by fawning all over him, holding his hand, and what respect have we got as a result of it?”

Meanwhile, Jeremy Corbyn, leader of Britain’s Labour Party, was set to speak before protesters gathered in Parliament Square after boycotting Trump’s visit.

“Tomorrow’s protest against Donald Trump’s state visit is an opportunity to stand in solidarity with those he’s attacked in America, around the world and in our own country — including, just this morning, @SadiqKhan,” Corbyn tweeted on Monday, referring to Trump lashing out at London Mayor Sadiq Khan just before landing in the UK.

With Post wires