Students at a top London University have banned the Brexit-supporting Mayor of London Boris Johnson because of his “inappropriate” comments about Barack Obama’s “heritage”.

Student leaders at King’s College London claimed the Mayor of London’s reference to the U.S. president’s “part-Kenya” heritage showed “disrespect” towards the most powerful man in world and was not “tolerant”.

Mr. Johnson had been due to address a student group called King’s Think Tank. However, in an email sent to him yesterday afternoon, organisers claimed:

“The level of discourse over the past few days does not meet the bar we set for these events nor do we feel does it help the British people in making the most momentous decision of our lifetime.”

“Furthermore,” they add, “we believe it does not reflect the true greatness of the United Kingdom, a land of tolerance, respect and fair play towards all”.

Next part of #borisjohnson backlash of his Obama ancestry comments. Kings College letter withdrawing #EUref invite pic.twitter.com/OUYyQyYDw1 — Ryan Heath (@PoliticoRyan) April 24, 2016

The students refer to an article Mr. Johnson wrote for the Sun about Mr. Obama removing a bust of Winston Churchill from his office.

“Some said it was a snub to Britain. Some said it was a symbol of the part-Kenyan President’s ancestral dislike of the British empire – of which Churchill had been such a fervent defender”, he wrote.

Continuing: “Some said that perhaps Churchill was seen as less important than he once was. Perhaps his ideas were old-fashioned and out of date”.

As has been reported extensively, the British imprisoned Barack Obama’s grandfather, Hussein Onyango Obama, during Kenya’s Mau Mau uprising – where thousands of white settlers, including women and children, were kidnapped and murdered.

The U.S. President has since hit back at Mr. Johnson’s comments, insisting that: “I love the guy [Winston Churchill].”

Mr. Johnson’s address was part of a series of up-and-coming events on the EU referendum, with other confirmed speakers including include John Mills, the leader of Vote Leave, Tim Farron MP, Leader of the Liberal Democrats and Labour MP, Chuka Umunna.

The ban, or “withdrawal of invitation”, is just the latest case in a series of high profile speakers to be blocked from speaking at British universities. These include biologist Richard Dawkins, feminist Germaine Greer, gay rights campaigner Peter Tatchell and PEGIDA UK organiser Tommy Robinson.

In all of these cases, students have claimed that they have not “banned” or “censored” the speaker when they block them from speaking.

Spiked Online’s Brendan O’Neill, a champion of free speech, took to his Facebook account to declare:

“Well, here you go. Students at King’s College London have No Platformed Boris Johnson because he exhibited a “tone of disrespect… in relation to the President of the United States of America”. So they’re now censuring people for having the temerity to criticise the most powerful man on Earth. Next time one of these campus censors claims to be super rad and progressive, remind them of this — that they punished a politician for disrespecting the American president. They may have purple hair and say the f-word a lot, but these Safe Space Stalinists are the footsoldiers of orthodoxy and conformism.”

The Sunday Times reported this weekend that “No-platform” policies are potentially illegal according to advice commissioned by the National Union of Students.

The 37-page legal opinion, by Christopher McCall QC, says such policies are legal only if applied to members of proscribed groups such as terrorists.

In other cases they breach section 43 of the Education Act 1986, which requires universities and, by extension, student unions to ensure freedom of speech.