If ever there were an example of someone that David Cameron would prefer to be ‘standing inside the tent pissing out rather than standing outside the tent pissing in’ come the 2015 General election it’s Boris Johnson. Suddenly, a tasty berth has opened up inside the Tories’ tent, with the announcement that Sir John Randall will be stepping down from his Uxbridge and South Ruislip seat, with its 11,000 majority, at the next election. This would give Johnson a safe seat near his home in London, which would mean he could spend more time on the national campaigning that Cameron so desperately needs him for if he is to win the next election.

A Tory beloved of both right and left wing – having been voted in as Mayor of London by the notoriously left-wing metropolitan electorate yet still regarded as ‘one of us’ by many of the more rabid right of the Conservative party due to his Eurosceptic views, Johnson is generally regarded as someone who can make a big difference for his party. Yet, whilst returning to the national party fold at the 2015 election will undoubtedly be in the best interests of David Cameron and arguably in the best interests of the party, it may not be in the best interests of Johnson, and here’s why.

First of all, he made a promise to serve as London Mayor until 2016. He said he would need the full four years to deliver what he has promised to, which is ‘to lead them out of recession, bring down crime and deliver the growth, investment and jobs that this city so desperately needs. Keeping that promise cannot be combined with any other political capacity.’ If he backed away from that ‘solemn vow’ to get into Parliament before 2016 it will reflect very badly on one of ether few politicians to have risen above the nationwide ‘anti-politics’ sentiment.

Secondly, Boris Johnson wants to be leader of the Conservatives. One day, he wants to be Prime Minister. If the Conservatives win the next election, there is unlikely to be a leadership election for quite a while, at least until after the 2017 a EU referendum, particularly if they win a majority and don’t have to form a coalition. Johnson now has proper executive leadership experience and will not want to be kicking his heels within Cameron’s cabinet for too long. Couple this with the fact that if he stands in the 2015 election he would be breaking his mayoral election promise, he would be better staying out of Parliament for a while in that case.

Should the Tories lose, then whilst there would be a leadership election much quicker, so it would be more useful for Johnson to be in Parliament at the time, he would still have the solemn vow hanging over him, and it would hang over him. Plus, he would be tainted by having been involved in a losing general election effort, ending a decent winning streak. He would have had to speak up for Cameron’s policies, the ones that had lost the election, and he would be less able to escape from them.

The truth is that the Tories won’t hold a Leadership election without Johnson. Should it be needed there are quite a few Tory MPS who would stand down to make way for him in a by-election. If he is going to not serve until 2016, it would only be accepted and understood if it were to specifically apply for the leadership of the party. So he should bide his time and stay out of it.