President-elect Donald Trump has promised to make big changes when it comes to US foreign policy. But, as of this week, it seems he may also have some thoughts on British foreign policy.

He shared one insight on the topic Monday. Not in a meeting with the prime minister, or a confidential memo to the British Embassy. But on Twitter.

Trump tweeted that the British should choose a new ambassador to the United States, and he knows someone who would do a "great job" — Nigel Farage.

Many people would like to see @Nigel_Farage represent Great Britain as their Ambassador to the United States. He would do a great job!

— Donald J. Trump (@realDonaldTrump) November 22, 2016

Farage is the leader of the right-wing UK Independence Party, the driving force behind Britain's controversial campaign to leave the European Union. He is also a fierce opponent of British Prime Minister Theresa May and the Conservative Party she leads.

Tuesday, Farage himself seemed shocked by Trump's vote of confidence, calling it a "bolt out of the blue" and a "surprise." He also said he thought he didn't have the diplomatic skills needed for the job. 

There is another small problem with the Trump plan: Britain already has an ambassador to the US. His name is Sir Kim Darroch, and he is one of the country's most senior diplomats. In Parliament, Foreign Secretary Boris Johnson made the same point, saying Darroch is a "first-rate ambassador," and that there is "no vacancy for that position."

But perhaps the bigger obstacle to Trump promoting Farage into the embassy is the fact that the British, like most nations, prefer to choose their own diplomatic staff. Sir Christopher Meyer, British ambassador in Washington during the George W. Bush years, put it this way to the BBC.

"You cannot [allow] the receiving power [to] decide who is going to be appointed as ambassador for your country. And it is completely unprecedented for a president-elect to suggest who he would like to see as British ambassador in Washington."

Meyer also told The Independent, “So the notion that you can sack a first-rate ambassador to replace him with a politician who is at odds, most of the time, with Theresa May and her government and would be beholden to Trump is barking mad.”

From PRI's The World ©2016 PRI