The Sun's move to back a British exit from the European Union is a major development in the campaign and could be seen as crucial. The top selling tabloid would have done its homework and decided that the chances of a "Leave" vote later this month are high.

The power of the Rupert Murdoch tabloid is not as strong as it once was but it is still an influential force and the "Leave" camp will be celebrating a major result. I was also quite amazed to see that one of Britain's leading businesspeople, James Dyson, the vacuum cleaner king, is also backing a British withdrawal. So what does this tell us? That there is a real possibility that by the end of this month Britain will be out of the European Union and that Prime Minister David Cameron will have quit. Boris Johnson could already be on his way to Number 10.

To some extent I blame Cameron. He has misjudged the British people on this issue and if Britain votes to stay in the EU it will be thanks to Labour voters not Conservatives. So the prime minister is in a very difficult situation. Perhaps he should consider his own position. If the polls are to be believed then it is thank you and good night for the PM, but those same polls this time last year said that he would not be prime minister either.

The referendum has effectively split the Conservative Party down the middle. Even The Sun, which backed Cameron at the last election, has deserted him. Interesting times.