Tory MP Douglas Carswell revealed he had not told David Cameron he was defecting to Ukip.
Carswell "I've not yet spoken to the Prime Minister...if I'd phoned him up beforehand you'd have heard about it in another way"
The Prime Minister and Mr Carswell's relationship has not always been friendly, with Mr Cameron once telling the Clacton MP he needed to "get a sense of humour".
ITV News Political Correspondent Paul Brand is following updates from the special Ukip press conference at which Mr Carswell is speaking.
Carswell says he thinks members of his local party will come with him. But feels sad to be leaving them.
More top news
Further one in eight expect to be aged between 71 and 80 years when they finally stop work, according to survey.
The team behind an irreverent US card game made more than $71,000 by giving people the chance to pay $5 without getting anything in return.
Cuts and rising cost of adult social care will leave councils underfunded, warns Local Government Association.