A giant 20-foot balloon depicting an orange and angry baby Trump in a nappy will rise above Parliament Square Gardens tomorrow after London Mayor Sadiq Khan led Greater London Authority gave permission for it to fly.

Trump was flying over after a fraught North Atlantic Treaty Organisation summit in Brussels where he piled pressure on allies to double their defence spending.

"Yes, there might be protests", he said.

Trump "has proudly sparked passionate often divisive emotions about things, I think Americans living here to eager to turn out and express their views", he said.

May hopes Trump, who landed at Stansted airport before flying by helicopter to the US ambassador's London residence, will help to accelerate a future free trade deal, though his public comments on Brexit cast a shadow over the visit.

On reaching the residence the pair walked across the lawn hand-in-hand.

Yet Trump's schedule will largely keep him out of central London.

"The President is not avoiding anything", he said.

"There is no stronger alliance than that of our special relationship with the USA and there will be no alliance more important in the years ahead", May said in a statement.

Despite not being an official state visit, the Government is desperate to ensure the USA leader feels he is being treated with the appropriate level of pomp and ceremony.

On Thursday, Trump will travel to Blenheim Palace, the 18-century stately home where Britain's World War Two leader Winston Churchill was born and spent most of his childhood. Some plan to stage an "all-night noise protest" outside the barricades surrounding Winfield House later Thursday, with those attending urged to "bring pots, drums and vuvuzelas".

A statement on the U.S. embassy website warns USA citizens to "be aware of your surroundings (and) exercise caution if unexpectedly in the vicinity of large gatherings that may become violent".

He said: "It's fine".

Queen Elizabeth II has outlasted 13 U.S. presidents during her reign. She said they will discuss security and defense, an aspect of the relationship that is causing anxiety for some British politicians.

He arrives about a year and a half after Prime Minister Theresa May invited him for a state visit, an invitation that was met intense opposition in the United Kingdom - nearly 2 million people signed a petition to rescind the invite.

"I think they like me in the UK".

"I'm excited to welcome the President of the United States", says Drew, who's 21.

Blimp organizer Leo Murray said it had been created to speak to Trump "in a language that he understands, which is personal insults".

We're more than used to our best sports-stars and celebrities being picked up as "British" in the English media when they're on the rise, and "Irish" when they're underperforming or in trouble. "You need to be a part of saying no to some of these people".

"However, let's not throw Trump Baby out with the bathwater - he'd be a welcome sight at any of the many protests happening across Scotland over the course of the visit".

Other protests - including several "family friendly" gatherings - will take place at every place he will visit over the coming days.

And he made clear that he did not approve of the softer stance the PM has been advocating despite fury from many Tory MPs.

The president is expected to head to Scotland on Friday night and spend the weekend at his Turnberry golf resort in South Ayrshire.

Trump is due to leave Britain on Sunday for talks in Helsinki the following day with Russian President Vladimir Putin, whose government stands accused by May's of unleashing a lethal nerve agent in the city of Salisbury.