Thousands expected to take the day off work to protest the state visit by US President Donald Trump.

The infamous Donald Trump baby blimp has once more taken to the skies ahead of a day of protests in central London.

The six-metre rubber inflatable will lead thousands of Londoners lining the streets of the British capital in rallies against the state visit by the US president.

A team of organisers wearing red jumpsuits and hats marked “Trump Babysitters” launched the balloon – which is the focus of an acquisition bid by at least one London museum – to cheers from dozens of onlookers at Parliament Square, where nearby roads are sealed off and police are standing guard in anticipation of large demonstrations.

Shaista Aziz, from the Stop Trump Coalition, said the blimp of the nappy-clad president clutching a mobile phone had “captured the world’s imagination”.

“We know that this will definitely annoy Trump,” she said.

Organisers of the Together Against Trump protest have billed it as a “carnival of resistance”, with demonstrators gathering at Trafalgar Square from 11am (10:00GMT) to declare a “Trump-free zone”.

A five-metre high talking robot effigy of the US president sitting on a golden toilet was also attracting onlookers. It repeated the phrases “No collusion”, “You are fake news”, and “I’m a very stable genius” – the audio of which is Trump’s own voice.

Protests have been billed ‘a carnival of resistance’ by organisers [Clodagh Kilcoyne/Reuters]

On Tuesday morning, Trump met with Prime Minister Theresa May. The meeting, which had been expected to be a wide-ranging discussion taking in the UK’s awarding of 5G infrastructure projects to Chinese tech giant Huawei amid a Washington-Beijing trade war, had been downgraded in recent days following May’s announcement of her resignation.

In another break with diplomatic protocol, having already launched a Twitter tirade at London Mayor Sadiq Khan, Trump endorsed Boris Johnson as May’s successor. Wading into the Brexit debacle, Trump will meet Michael Gove, a cabinet minister also in the running to be the next Conservative leader, in a private meeting on Tuesday.

Climate change activists, students, pacifists, trade union members and families are expected to join those gathering in central London, while the protesters include Handmaids Against Trump – women draped in red with white hoods in homage to Margaret Atwood’s dystopian novel about a crackdown on reproductive rights.

A huge police and security operation was under way with protesters barred from demonstrating directly outside Downing Street and road closures in place.

Labour leader Jeremy Corbyn will address those demonstrating on the second day of Trump’s visit.

Corbyn, who boycotted a state banquet on Monday thrown in honour of the president, said he would join crowds to “stand in solidarity with those he’s attacked in America, around the world and in our own country”.

The Liberal Democrats and Green Party are appealing to the public to join the protests.

This talking robot depicting the US president tweeting on the toilet utters phrases such as ‘No collusion’ [Clodagh Kilcoyne/Reuters]

Trump supporters were also taking to the streets.

Lewis Metcalfe, 28, from Richmond in North Yorkshire, said he took a day off work to travel to London and offer “a difference of opinion”.

“I’m obviously going to be a minority today. I’m not here to troll, to cause a riot or cause disruption,” he said at Parliament Square, wearing a Make America Great Again cap.

“I don’t agree with all his policies. He’s not the greatest president in the world but he does get things done.

“I think it [the protest] is a little bit hypocritical because you get hundreds of thousands of people for Donald Trump today and yet we had minuscule, maybe hundreds of people, for Xi Jinping and Mohammed bin Salman.”

Scotland Yard’s Deputy Commissioner Sir Steve House told the London Assembly Police and Crime Committee on Tuesday the policing plan has so far worked “effectively”.

He said the force was not in a position to estimate how much the operation will cost but added that the US president’s last visit to the capital cost about £2.9 million ($3.7m) to police.

About 250,000 anti-Trump activists gathered when he visited the UK as US president for the first time on July 13 last year, with the blimp making its maiden flight.

Elsewhere across the UK, protests are also planned in Birmingham, Stoke, Sheffield, Glasgow, Edinburgh, Chester, Leicester, Oxford and Exeter.

On Monday, several visual protests were staged as the president touched down on British soil.

Amnesty International unfurled five banners on Vauxhall Bridge in view of the US Embassy in London, and a projection comparing Trump’s UK approval rating with that of former president Barack Obama was shone on the Tower of London, organised by anti-Brexit protest group Led By Donkeys.