Video report by ITV News Political Correspondent Carl Dinnen
US President Donald Trump has confirmed he has cancelled his trip to London, saying he did not want to cut the ribbon on the new US embassy as he deemed the building's relocation a "bad deal".
He was due to visit London in February for the opening of the new £734 million building.
Writing on Twitter, Mr Trump said he was "not a big fan" the embassy's move from Grosvenor Square to Nine Elms, south London, blaming the previous administration.
The United States announced plans to move from its current embassy building in Mayfair in October 2008 during George W Bush's Administration - several months before Barack Obama took office.
On the embassy web page about the project, it said: "The project has been funded entirely by the proceeds of the sale of other US Government properties in London, not through appropriated funds."
The new building will open for business on January 16.
On Friday morning Downing Street said the "strong and deep" partnership between the UK and US "will endure", despite Mr Trump's cancellation of the trip.
British government sources said they had never officially been informed of a date for Mr Trump to make a visit, but speculation had suggested he would formally open the embassy at a ceremony in February.
Mrs May controversially extended the offer of a state visit, officially on behalf of the Queen, when she became the first world leader to meet Mr Trump in the White House following his inauguration last year.
"Our position is that an offer for a state visit has been extended and accepted," a Downing Street spokesman said, with the expectation Mr Trump will visit Britain later this year.
Reports have suggested Mr Trump was backing away from the visit over fears of mass demonstrations.
Mrs May and Mr Trump fell out in November over his retweeting of anti-Muslim videos posted online by the deputy leader of the far-right Britain First group, Jayda Fransen.
At the time, the PM said Mr Trump was "wrong" to retweet the videos, and the president hit back at May on Twitter by telling her to focus on "destructive radical Islamic terrorism" in the UK, rather than on him.
London Mayor Sadiq Khan, who has clashed with Mr Trump in the past, said the US president had "got the message" that many Londoners did not approve of his policies and actions.
Foreign Secretary Boris Johnson hit back at Mr Khan, accusing him and Labour leader Jeremy Corbyn of trying to damage the relationship between Britain and the US.
Brendan Cox, widower of murdered Labour MP Jo Cox, echoed suggestions that concerns about protests may have been the real reason for the visit's cancellation.
Tom Tugendhat, chairman of the Commons Foreign Affairs Committee, suggested that Mr Trump was more aware of opposition in the UK than in other countries he had visited because it was expressed in English.
"While I think it's a shame, I think - if I'm honest - it more reflects the fact that other people criticise in French, Italian, Korean and other languages and we criticise in English, and it's much easier for him to read English," he said.