Over the next three days, U.S. President Donald Trump arrives in the UK for the start of his state visit. This trip will include a formal meeting with Queen Elizabeth II.

The U.S. and the UK have enjoyed a "special relationship" since the World Wars with a common language, shared history and geopolitical views. The special relationship has always been something more prized by the smaller UK than its more powerful American offspring but recognized by both as a strategic asset during and after the Cold War.

British Prime Minister Theresa May readily appealed to this special relationship when rushing off to be the first foreign leader to meet with Trump in the White House. Her objective was to get his support for a new trade deal post-Brexit.

Pro-Leave supporters regularly point to the gains of closer economic cooperation with the United States that Brexit could make possible as a key reason to leave the European Union. Indeed, May's swift offer to Trump of a state visit was rumored to be an effort at winning concessions on a more favorable trade deal.

The problem with this is that – like any relationship – it takes two and Trump is not a committed partner. Before his previous visit and now ahead of his new visit, Trump pours more praise on May's political rivals like current Tory leadership contender Boris Johnson.

It is Johnson that is said to be an excellent prime ministerial material without any mention of May. This only weakens her standing as it seems to have done little to dent her enthusiasm for getting a deal with Trump.

Trump's latest gaffe in signaling his explicit support for Johnson over other contenders is an unprecedented interference by a U.S. president in a UK electoral matter that has already begun backfiring. The front runner at the start of a Tory leadership contest has never won before and Trump's intervention may have helped unwittingly ensure that outcome.

The appeal to Trump on a Brexit deal is the stuff of Tory fantasies but has no basis in fact. Whatever one's view of Trump's abilities, it is undeniable that he sees himself, the author of the book "The Art of the Deal," as one of the world's greatest deal makers.

Such a title is not earned by being generous to your opponents. Trump's politics may be controversial but his campaign slogan of "America First" promising to end trade deficits with other countries and instead raise profits is not.

Taking these facts into account, it is difficult to see under what circumstances Trump would knowingly agree to a trade deal that might make the UK better off at America's expense. This might be a major boost to the Tories in Britain, but hugely damaging to Trump's re-election whose campaign is already underway. The special relationship will not deliver any special benefits for post-Brexit Britain under a Trump presidency.

While May has gone out of her way to avoid any direct confrontations with Trump – much to the disappointment of her political foes and friends alike – she has taken a very different approach to Huawei.

Trump's administration has been leading efforts to block Huawei as part of a larger trade war with China that has been much criticized around the world and within the United States.

His officials were stunned when news was leaked that May's government was going ahead with Huawei building non-core elements of a new 5G system. While there have been no concrete repercussions against the UK from its allies, there have been plenty of stark rebukes as Britain looks set to continue with its plans.

With protests across London expected to reach record proportions, Trump is unlikely to feel that the British public much values a closer connection to the U.S. under his leadership. May's position on Huawei mixed with Trump's re-election campaign make it almost certain that while there may be talks of a great future trade deal, Trump poses a renewed threat to the UK-U.S. special relationship that has survived over half a century.

The now unprecedented protests in the UK against a visiting U.S. president could become the new norm of a more strained and less supportive future relationship between the two allies. If Trump were to win a second term, this may set a new tone for years to come.