At a meeting with staff on Tuesday he said: “This is a moment and a chance to do it, and if I don’t do it now, I never will.”
His new company is expected to focus on comment and analysis – with the fall-out from Brexit set to drive much of the output.
Last month Mr Harding took part in the Board of Deputies annual dinner, interviewing Scottish Opposition leader Ruth Davidson, who has been mooted as a possible future Tory leader.
In 2011 at an event organised by the JC at the JW3 centre, Mr Harding declared his support for Israel.
He said: “I am pro-Israel. I believe in the State of Israel. I would have had a real problem if I had been coming to a paper [The Times] with a history of being anti-Israel. And, of course, Rupert Murdoch is pro-Israel.”
Mr Harding grew up in north-west London as the grandson of a German Jewish refugee.
Educated at St Paul's in Hammersmith, one of the top private schools in London, and Cambridge, where he got a first-class history degree, he started his journalistic career at the Financial Times in 1994.
He went on to work in China and then become the FT's media editor.
