Ben Roback is Head of Trade and International Policy at Cicero Group.

It is an unfortunate state of affairs when political leaders have their views of foreign cities influenced by social media agitators and bullies. “Free speech!”, yell those who wish to use Twitter as a platform for spreading their most provocative and angry ideas, and they are of course correct. Social media exists as a platform for thoughts, discussion and hot takes, only moderated to ensure rules and basic standards are upheld. But that needn’t mean that some of social media’s most prominent antagonists should have an audience with the world’s most influential politicians; we are all free to follow whomever we wish, but it is unfortunate that the President of the United States is having his views on London – the greatest city in the world – influenced by controversial commentators.

President Trump’s remarks on Twitter have influenced the Conservative leadership contest, pushing candidates into either defending Sadiq Khan or agreeing with the president’s criticisms of London and the Mayor. Jeremy Hunt said he would not have used the same words as Trump, but he would “150 per cent agree” with the overall sentiment. Taking a deeply critical approach, Sajid Javid said the President should “stick to domestic politics”. Michael Gove mildly criticised the president, saying “I think it always a mistake to retweet anything that Katie Hopkins tweets.” Rory Stewart tweeted that he “100 per cent disagrees with both the language and the sentiment”.

As President Trump formally launches his 2020 re-election campaign, we can guarantee he will continue to single out his political enemies. In 2016 that was Hillary Clinton. Looking ahead to November 2020, the figures of fun will be the likes of Robert Mueller, Bernie Sanders, Joe Biden, Elizabeth Warren – and perhaps Khan. Mr Trump’s isolation of political opponents worked in 2016 and could be repeated again. That shines a spotlight on relations between Washington and London, which desperately need improving.

The answer could lie in the winner of the Conservative leadership contest

Boris Johnson, the current frontrunner, is reportedly a friend of Trump. Their relationship has recovered remarkably since 2015, when the then-Mayor of London said Trump was “out of his mind” over comments about radicalisation in London. The two are now allies, and the similarities are clear – blond, bold and pro-Brexit. In his state visit earlier this month, Trump said of Boris “I like him, I’ve liked him for a long time and think he’d do a very good job”. Jeremy Hunt also spent time with the President’s team during the London visit and Michael Gove enjoyed an extensive interview with him in January 2017. For Sajid Javid the relationship is less warm, after he said it was “odd” to have been excluded from the state banquet held for the president. Asked if he thought his exclusion was due to his Muslim background, Javid said “I am not saying that at all. I really don’t know.”

A new Tory leader and prime minister offers something of a chance to reset the relationship between London and Washington, building on the positives emerging from the June state visit. Until then, the relationship between London and Washington will remain in dire straits. Khan recently called Donald Trump a “poster boy for racists” after the President tweeted “London needs a new mayor ASAP. Khan is a disaster – will only get worse!”. It couldn’t be clearer that the two dislike each other and any semblance of a relationship is beyond repair. Barbs will continue to be exchanged and leading Conservatives will continue to be asked whether they side with the President or are happy to stand by in the face of personal criticisms.

But there should be no doubt amongst politicians of any party or country. London is not “Londonistan”. London is not “stab city”. The best city in the world faces challenges of knife crime in the same way that most US cities are grappling with the ongoing challenge of gun crime. We are diverse, unique and imperfect. We are open to the kind of criticism that is protected by a right to free speech. We should celebrate what is great about our capital and challenge what needs to be improved. The 2020 London mayoral election provides fertile ground for that debate.