US President Donald Trump can wager on an uncomfortable reception when he meets Queen Elizabeth during his long-delayed inaugural trip to Britain next month.

US Ambassador to the United Kingdom Robert Wood Johnson announced the planned meeting between the President and the monarch while speaking on Sky News UK on Thursday morning (Australian time).

“Yes, yes, I mean, he has to see the head of state,” Mr Johnson said.

“Putting his foot on British soil, it’s job one. It’s very important, very symbolic.

“Meeting Her Majesty is the most important thing, because she’s the head of state, and from then on it’ll be what the President wants to do.”

Mr Johnson did not give details of when and where the meeting would take place.

Mr Trump has previously said his mother, who was born in Scotland, was a “big fan” of the Queen, The Sunday Times reported.

But while Mr Trump may be looking forward to meeting the Queen, his visit to the UK from July 13 is set to be less than cordial, with protests against the President’s domestic and international policies already planned.

One group of activists have started a petition and a crowdfunding campaign to fly a giant ‘Trump Baby’ blimp above Parliament House in protest.

“Donald Trump is a big, angry baby with a fragile ego,” founder Leo Murray said in a statement explaining the planned protest.

“He’s also a racist demagogue who is a danger to women, immigrants and minorities and a mortal threat to world peace and the very future of life on earth.

“Moral outrage is water off a duck’s back to Trump, but he really seems to hate it when people make fun of him.”

Activists want to fly this six-metre-high “inflatable baby” with a “malevolent face and tiny hands” over London when Mr Trump visits. Photo: Trump Baby

Mr Trump was originally set to visit the UK in January to mark the opening of the new US Embassy in London.

While that trip was ostensibly scrapped at the last minute after the President expressed his dissatisfaction at the building’s location and cost, many commentators described it as a move to avoid his exposure to protests.

London Mayor Sadiq Khan this week defended the right of residents to protest about the President’s visit while speaking to singer Jessie Ware on a podcast.

“It’s right and proper for us to be active citizens and to march and to lobby and to protest,” said Mr Khan, who has previously traded barbs with Mr Trump on social media.

“It should be peacefully. We can’t have anybody who thinks it’s OK to cause criminal damage or to cause harm,” he said.

“Done properly, it’s really important.”

Mr Khan found himself on the receiving end of one of Mr Trump’s angry tweets last year after the deadly terror attack at London Bridge and Borough Market.

Following the attack, Mr Khan told Londoners they would see an increased police presence and urged people not to be alarmed by the extra officers.

Mr Trump decided to berate Mr Khan for his comments, tweeting: “At least 7 dead and 48 wounded in terror attack and Mayor of London says there is ‘no reason to be alarmed!'”

Mr Trump most recently sparked anger throughout the UK for his policy of separating migrant children from their parents at the United States-Mexico border after photos of the unaccompanied children caged at a detention centre.

British Prime Minister Theresa May on Wednesday declared the US was wrong to separate migrant children from their parents, but rejected calls to cancel Mr Trump’s visit.

Ms May described images of children in cages as “deeply disturbing”.

“This is wrong. This is not something that we agree with.”