Nigel Farage, the interim leader of the U.K. Independence Party, gets on an elevator at Trump Tower on Saturday in New York. (Evan Vucci/AP)

LONDON — It came as something of a shock to the British establishment that President-elect Donald Trump backed Nigel Farage to become the British ambassador to the United States.

Throwing diplomatic protocol out the window, Trump tweeted overnight that Farage would do a “great job!” as Britain’s top diplomat in Washington.

It was an extraordinary intervention from the president-elect, and Downing Street didn’t waste much time in dismissing the idea and pointing out the seemingly obvious: Britain already has an ambassador in Washington. Kim Darroch, a former national security adviser, took up the post in January.

“There is no vacancy,” a Downing Street spokesman said in a short statement. “We already have an excellent ambassador to the U.S.”

It’s simply unheard of for an incoming U.S. president to suggest who could be Britain's representative in Washington. Indeed, one British lawmaker joked in the House of Commons on Tuesday that perhaps Britain, in a reciprocal move, could suggest having Hillary Clinton as the next U.S. ambassador to the U.K.

British Foreign Secretary Boris Johnson dismisses U.S. President-elect Donald Trump's unprecedented expression of support for Brexit campaigner Nigel Farage to be made British ambassador to Washington, saying pointedly in parliament that there is no vacancy for the job. (Reuters)

Writing on the right-wing website Breibart News, formerly run by Trump senior adviser Stephen K. Bannon, Farage said Trump’s backing was like a “bolt from the blue.” But in the same piece, he suggested that perhaps it wasn’t a total shock, given that others had told him that Trump is a man who values loyalty.

Farage is the interim leader of the anti-immigrant U.K. Independence Party (UKIP), a frequent critic of the British government and a leading figure in the successful campaign for Britain to leave the European Union, otherwise known as Brexit.

In recent days, senior British politicians have gone on a Trump charm offensive, painting the president-elect as someone with whom they can work and do business.

“I think we should regard it as a moment of opportunity,” British Foreign Secretary Boris Johnson said recently when asked about a Trump presidency. It was a strikingly different tone than Johnson had struck last year, when he blasted Trump’s “stupefying ignorance,” saying it made him “frankly unfit” to be president.

Farage, however, went out on a limb for the business tycoon long before Election Day. He joined him on the campaign trail. He loudly predicted a Trump victory. He was so convinced that Trump would prevail that he said he placed a “pretty big bet” on the outcome.

He was also the first foreign politician to meet with Trump, posing next to him in front of a gilded elevator at Trump Tower just four days after the election. At the meeting, Trump reportedly encouraged Farage and associates to campaign against offshore wind farms that would obstruct the view from one of his two golf courses in Scotland.

Andy Wigmore, a media consultant for one of the campaigns to leave the E.U., was at the meeting with Trump and Farage.

He told the Express, a British newspaper, that they “covered a lot of ground during the hour-long meeting we had.”

Wigmore added: “But one thing Mr Trump kept returning to was the issue of wind farms. He is a complete Anglophile and also absolutely adores Scotland which he thinks is one of the most beautiful places on Earth. But he is dismayed that his beloved Scotland has become over-run with ugly wind farms which he believes are a blight on the stunning landscape.”

Wigmore told the New York Times that members of his group had opposed wind farms even before the meeting with Trump but that the president-elect “did suggest that we should campaign on it” and “spurred us in and we will be going for it.”

Last year, Trump lost a lengthy legal battle against the development of an offshore wind farm close to his Aberdeenshire course, Trump International Golf Links.

On Tuesday, Farage did not comment on any such wind farm discussions, but he emphasized that Trump is a man who sticks by his friends.

“I can still scarcely believe that he did that though speaking to a couple of his long time friends perhaps I am a little less surprised,” Farage wrote of Trump's endorsement of him as a British ambassador. “They all say the same thing: that Trump is a very loyal man and supports those that stand by him.”