UPDATE: King's Think Tank has said the email to Boris Johnson was sent without the knowledge of its student committee, though the society would not say who sent the email. "We decided not to publicly state who sent it because we prefer to settle these matters internally," the society's president wrote in an email.
The Think Tank club at King's College London is hosting a series of events in the run-up to June's EU referendum and had invited Johnson to attend to represent the Vote Leave group.
But after the London mayor made controversial comments about "part-Kenyan" Barack Obama, the society withdrew its invitation, citing concerns around tolerance and respect.
The furore began on Friday, when Johnson said the "part-Kenyan" President Obama had purposefully removed a Winston Churchill bust from the Oval Office because of his "ancestral dislike of the British Empire".
An email written to Johnson, signed by Kings College Director of EU Referendum Events, and the society's president and vice-president, said his "inappropriate" comments about Obama's heritage "does not reflect the true greatness of the United Kingdom".
Read the email to Boris Johnson in full, below.
Dear Mr Johnson,
Given your inappropriate comments and inferences towards President Obama's Kenyan heritage, of which he is rightly proud, and your general tone of disrespect over the past few days in relation to the President of the United States of America, we are now formally withdrawing your invitation at Kings College London.
We are looking forward to providing a forum for both sides in the EU Referendum Debate to argue their point of view without fear or favour. 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 we believe it does not reflect the true greatness of the United Kingdom, a land of tolerance, respect and fair play towards all.
Mike Molloy (Director of EU Referendum Events at Kings College London)
Margot MacDonnell (President of Kings College London Think Tank)
Erica Arcudi (Vice-President of Kings College London Think Tank)
People said the withdrawal of the invitation amounted to "no-platforming" Johnson.
However, it was reported that the decision to withdraw the invitation came before Boris Johnson had accepted the offer.
The withdrawal of the invitation has already been linked to the debate around freedom of speech on university campuses.
It comes after high-profile, so-called "no-platforming" incidents involving controversial speakers.
"No-platforming" is a policy of banning groups and individuals likely to cause controversy by appearing on campuses.
In March, academics and campaigners including Peter Tatchell, AC Grayling and Richard Dawkins supported a protest outside the National Union of Students headquarters in London.
Yet a survey for the BBC published on Monday found on a majority of students supported no-platform policy.
Some 66% of the more than 1,000 students surveyed said that no-platforming was acceptable in certain circumstances.