London voters vindicated that thinking when they turned out in record numbers to hand control over Britain's capital to a politician whose biggest asset is his larger than life personality.

The only problem for Labour is that Boris Johnson is a Conservative and his election marks a major step forward in the Tories' efforts to wrestle back power at Westminster.

Winning London changed the narrative of the local elections for the Conservatives. The charge levelled at David Cameron the morning after election night was that the party's council gains were the product of unhappiness with Gordon Brown, rather than positive votes for Tory policies.

It is much harder to say that about the outcome of the mayoral race.

Ken Livingstone has never been a Labour loyalist so Londoners had little reason to vote against him simply to hurt Gordon Brown. A protest vote in the mayoral election was also risky because, in such a close race, there was the very real prospect of it influencing the result. Livingstone himself said that people in the capital were making their choices based on London issues.

The simple fact is people chose a Conservative to run London because they preferred his policies to the alternative. Mr Cameron's challenge is to make sure that his party achieves this in constituencies up and down the country at the next General Election. How the Mayor of London performs will play a significant role in determining the Tories success.

Dissatisfaction with a Government is not enough to hand victory to its opponents, as Michael Howard discovered to his cost in 2005. Opposition parties have to convince the electorate they are competent to wield power too. The Tories now have the chance to demonstrate that competence in London where a Conservative administration will have an £11bn budget and implement policies on transport, crime, housing and the environment.


So the pressure is on Mr Johnson to prove that he is not just the affable toff who is only ever a short sentence away from committing another gaffe. He managed to stay out of trouble during the campaign for the mayoralty. Now he must maintain his discipline until the next General Election at least.

Johnson must do more than avoid lurid headlines about his personal life or making careless comments. He must actually lead. He, like Mr Cameron will, went into an election promising a break from the past and now has to deliver.

Critical to that success will be the people he surrounds himself with. It remains to be seen whether the suggestion that he will appoint Labour MP Kate Hoey as an Olympics adviser was anything other than a campaign tactic, but he needs a high calibre team to maintain tight control over every aspect of his wide-ranging brief.

If he is to help his party win a Westminster majority, Johnson must also follow through on his promise to be a mayor for the whole of London. The "donut" strategy to appeal to London's suburban voters, designed by Australian political consultant Lynton Crosby, might have held the key to winning the election numbers game but his policies must benefit all sections of the community.

It is inevitable that Labour will step up their attempts to undo Cameron's largely successful efforts to rid the Tories of their "nasty party" image. They will seize on any evidence, however weak, that the London mayor is defending the interests of the educated middle classes at the expense of others.

However well Johnson performs, his party leader must prepare now for inevitable crunch points that lie ahead. Johnson must put London first and that is likely to involve straying from the Conservative Party line. That tension even emerged during the campaign when Johnson proposed an amnesty for longstanding illegal immigrants.

One of Johnson's first acts as mayor will be to review the extension of the congestion charge when Cameron has hinted a future Tory government may embrace it as a method of funding new road building. Cameron must argue such policy differences demonstrate that the Conservatives believe in politicians answering to the people they serve first and their party second.

The Olympics could also pose major problems. Having enjoyed free reign to criticise the many failings that have characterised the event's organisation so far, the Tories now find their own fortunes inextricably linked with the success – or otherwise – of the 2012 Games.

When the project inevitably runs into further difficulties the public will not stop to find out exactly who is responsible – the Government, the organising committee and the mayor will all feel their wrath. As part of the team that won the bid, Livingstone was a passionate defender of the Games. As a newcomer, Johnson has scope to act more as a critical friend and it is in his own and his party's political interest that he adopts that approach.

Despite those dangers, Johnson's election brings with it huge potential for the Tories. Voters in London have put their reservations to one side and entrusted the Conservatives with substantial power. If Boris Johnson's administration is a success, voters across the country may well take notice and do the same in a General Election.