Nigel Farage has made an extraordinary pitch for a role helping build relations with Donald Trump, after the President-elect broke diplomatic convention to suggest the Ukip politician be the UK’s new US ambassador.

Mr Farage told Downing Street to accept him because “the world has changed” and then chided Number 10 for being “negative” about his involvement.

After Mr Trump’s intervention, which will be deeply uncomfortable for Theresa May, the Ukip MEP said it was time Number 10 accepted he was “in a good position” to help.

Ms May’s officials have consistently dismissed the idea of Mr Farage’s involvement, arguing that the Prime Minister and future president would have a Reagan/Thatcher-style connection in which there is no “third person”.

But writing for the right-wing Breitbart website, Mr Farage said: “I have said since the now famous photograph with Donald Trump ten days ago that I would do anything to help our national interest and to help cement ties with the incoming Anglophile administration.

“At every stage I am greeted by negative comments coming out of Downing Street. The dislike of me, UKIP, and the referendum result is more important to them than what could be good for our country.

“I have known several of the Trump team for years and I am in a good position with the President-elect’s support to help. The world has changed and its [sic] time that Downing Street did too.”

Mr Farage said Mr Trump’s tweet, suggesting him for the post of the UK’s US ambassador, came like a “bolt from the blue”, but that it was less of a surprise because the President-elect supports those who “stand by him”.

Turning his guns on Ms May, he said: “It is called trust and it is how the whole world of business operates. Sadly, the cesspit that is career politics understands nothing of this. In their world the concept of trust is transitory.

“The political revolution of 2016 now sees a new order in charge of Washington. In the United Kingdom the people have spoken but the players at the top have, I am afraid, stayed the same.

“Those who supported Remain now hold senior positions. Worst still, those who were openly abusive about Trump now pretend to be his friend.”

Boris Johnson: There's 'no vacancy' for US ambassador

Both Ms May, Foreign Secretary Boris Johnson and other senior Tories had made disparaging comments about Mr Trump during the election campaign.