Boris Johnson was blocked on his journey to Buckingham Palace by climate change protesters.
Police were forced to break up a human chain of people standing across the Mall, the road that leads to the palace.
Mr Johnson’s motorcade was travelling to the Palace to meet the Queen and officially take the office of Prime Minister.
Protesters wearing red t-shirts linked arms and stood in the way of Mr Johnson’s jaguar and police outriders.
Other protesters carried a large red banner which read “Climate Emergency.”
Motorbike officers dismounted to break up the protest.
The motorcade was stopped on the Mall for less than a minute while the protest was broken up. Mr Johnson then made his way to the palace for his first audience with the monarch.
Greenpeace claimed credit for the protest, tweeting: “We just tried to hand the incoming PM a crucial letter – it contains the answers to tackling the Climate Emergency.
“But will he *act*?”
John Sauven, Executive Director of Greenpeace UK, said: “Climate change needs to be front and centre of this new administration from day one.
“The responsibility on a Prime Minister to act on the climate emergency has never been greater.
“If we want any chance of leaving a habitable world to our children we need to see action start immediately. We can’t blunder and bluster our way out of this emergency.
“In reality the government is simply failing to tackle the climate crisis. It’s not enough to point to world-leading climate targets when too often government policy ignores or worsens the situation by supporting fracking and banning onshore wind. Boris Johnson must get to grips with the climate emergency or be remembered as the Prime Minister who jeopardised our children’s future”
Earlier, Mrs May’s farewell speech in Downing Street was interrupted by a cry of “stop Brexit” from a protester outside – in reply she joked: “I think not.”
Mr Johnson was due to give a speech at 10 Downing Street at around 4pm.
There was fury as he invited hard Brexiteer MP Priti Patel – sacked over off-the-books meetings in Israel – and former Vote Leave chief Dominic Cummings – th back into the fold as he ramps up his threat of a No Deal Brexit.
And Cabinet Remainers David Gauke, Rory Stewart, deputy PM David Lidington and Chancellor Philip Hammond all promptly resigned to fight a disastrous No Deal.
Mr Johnson met the Queen shortly after Theresa May visited Buckingham Palace and gave her resignation – with a coded warning to her successor.
The outgoing Prime Minister, who left with husband Philip by her side, told MPs at her final PMQs that politics is not about “eloquent speeches and media headlines” – it’s about real people.
But in a perfect metaphor for her leadership, she was forced to break off her speech to respond to a protester shouting “stop Brexit!”