So finally, after weeks of very public will he, won't he, London Mayor Boris Johnson, a former school friend and political ally of Prime Minister David Cameron, broke ranks and said he would join six other leading figures from the ruling Conservative Party in campaigning for Britain to leave the European Union.

Many see his move as a tactical one, aimed at securing first place in the queue to replace Cameron as prime minister when he steps down, as he said he would, at the next general election in 2020.

Lotsof analysts, including many who support Britain leaving the EU, believe Johnson's support would tip the balance in favour of an out vote.

Boris, they say, is one of Britain's best loved politicians and a future prime minister.

I don't think so. And here's why.

I am starting to feel that here we have a case of a celebrity politician who has started to believe in his own publicity.

If various press reports here are to be believed, Cameron was so keen to get Boris on side that he offered him various key jobs – foreign minister, defence minister and other plums.

Cameron came back from two days of intense negotiations in Brussels with a deal many believe will sway the vote in favour of staying, including a change to the treaty covering the modern EU which will specifically exclude Britain from moves in the EU for ever closer political union.

There's one key issue which the out camp, including the latest recruit Boris, seem to have forgotten; Britain's farming industry.

At present then UK's highly modernised agriculture industry, like others throughout the EU, is the recipient of various subsidies, designed to control the output of food.

Over the weekend I learned that some analysts believe only 10 percent of Britain's farmers would survive if the UK pulled out of the EU. And if the government had to make up the shortfall in subsidies, taxes would surely have to rise, as sure as eggs are eggs.

Boris and his new best friends – which include such publicly disliked figures as UKIP leader Nigel Farage and a maverick parliamentarian called George Galloway – have surely forgotten that.

And here's something else.

Boris deserves praise for his work over two terms as mayor of London, building the city into a strong, relatively prosperous metropolis with modern transport systems, which was the host of the highly successful Olympic Games of 2012.

But Boris has form.

He was sacked by the London Times newspaper in 1987 after he was found to have made up a quote, including erroneous information in it.

After becoming member of parliament for the prosperous town of Henley, west of London, he had a colourful career which included being sacked as the opposition Conservative Party's spokesman on the arts for what party leader Michael Howard said was the act of lying over the affair with a high-profile journalist.

Boris bounced back, become a highly successful mayor of London in 2008, although he is alleged to have offended his Chinese hosts in Beijing at the closing ceremony of the 2008 Olympics by appearing with his jacket casually undone.

Latest opinion polls, including a poll of polls in the newspaper Johnson regularly writes a highly paid column for, the Daily Telegraph, show those in favour of staying at 54 percent, with those in favour of a British exit at 46 percent.

Call it a gut feeling, but I think Boris may have picked the wrong side. If the vote goes in favour of Britain remaining, the mayor of London, whose term ends in May, could well find himself back in the political wilderness.

Chris Peterson is managing editor of China Daily UK; [email protected]