Police have dropped their investigation into an interview in which historian Dr David Starkey made controversial comments about slavery.
Dr Starkey made the remarks on YouTube to conservative commentator Darren Grimes, who was also investigated.
The historian accused the police of a “misconceived, oppressive” attempt to curtail freedom of expression.
He has previously apologised for saying in June that slavery was not genocide because “so many damn blacks” survived.
“It was a serious error for which I have already paid a significant price,” he said last week.
“I did not, however, intend to stir up racial hatred and there was nothing about the circumstances of the broadcast which made it likely to do so.”
The Metropolitan Police opened the investigation at the end of September, almost three months after an allegation of a public order offence was passed to them by Durham Police.
Last week, the Met said a senior officer had been appointed to review the investigation.
In a statement on Wednesday, Cdr Paul Brogden said: “It is the duty of police to assess and, if appropriate, fully investigate alleged offences and the public would expect us to investigate an allegation of this nature.
“We conducted initial inquiries to establish the full circumstances and sought early advice from the CPS. Having had the opportunity to review this, it is no longer proportionate that this investigation continues.
“We have made direct contact with the individuals involved and updated them on this decision.”
In response, Dr Starkey said: “The investigation should never of course have begun. From the beginning it was misconceived, oppressive and designed to misuse the criminal law to curtail the proper freedom of expression and debate.
“This freedom is our birthright; and it is more important than ever at this critical juncture in our nation’s history.” The outcome was also “a personal vindication”, he added.
Writing on Twitter, Mr Grimes described it as a “vexatious charge” that had involved the “unprecedented use of the Public Order Act to regulate speech & debate”.
During the original discussion, Dr Starkey told Mr Grimes that slavery “was not genocide” because “otherwise there wouldn’t be so many damn blacks in Africa or Britain would there? An awful lot of them survived.”
The subsequent outcry led Cambridge University’s Fitzwilliam College, Canterbury Christ Church University, The Mary Rose Trust and publisher HarperCollins to cut ties with him.
But figures from former home secretary Sajid Javid to ex-Liberal Democrat leader Tim Farron and former director of public prosecutions Lord Macdonald of River Glaven criticised the investigation into Mr Grimes as a threat to a free media.