It is understood that under the terms of his departure he is unable to launch the consultancy until the 2012 and will now work at News International until that time.
He joined Tulchan from Brunswick in 2000, having worked as an associate partner in New York and London from 1994. During that period he spent two years on secondment to the Department for Culture, Media and Sport, where he was a special adviser to Virginia Bottomley.
It is thought that Honnor will report directly into News International's new CEO Tom Mockridge.
News International came under further pressure earlier this week when it was reported that the company continued to make payments and provide benefits to former News of the World editor Andy Coulson while he was serving as director of comms for the Conservative Party.