London mayor Boris Johnson is likely to "defy political gravity" and win a second term in the City Hall, experts said here on Thursday, just one week ahead of the city's mayoral election on May 3.

The Conservative Boris Johnson was a surprise winner in the last London mayoral elections in 2008, when he beat the veteran and two-time mayor Ken Livingstone, who is the Labor Party's candidate this time round.

"Boris is a teflon politician, nothing sticks to him," said the London School of Economics (LSE) Professor Patrick Dunleavy.

"He seems to defy political gravity -- Boris is a wonderfully charismatic person; he is rather endearing. He manages to get a lot of personal warmth and empathy into the way he relates to people. That is the essential basis of his appeal," Dunleavy told Xinhua.

But he added that Boris has not really done a lot as London mayor. "It is not at all clear what he would do if he got another four years as London mayor. It would just be a continuation of current policies," he said.

It was difficult to pin down Johnson's strategies -- there were some small scale initiatives, said Dunleavy.

For instance, he had copied a scheme from France for an extensive network of bikes for hire on the streets.

"That's been a big success but it is a very small policy," said Dunleavy.

Johnson's main contender is Livingstone, who led the former London-wide municipal authority the Greater London Council (GLC) until is was abolished by Mrs Thatcher in the 1980s.

He staged a political comeback, first as an MP and then as the first London mayor, running against his own Labor Party's candidate in 2000 and winning.

"He is quite an elderly politician by the standards of British politics nowadays. And he had been looking a little bit tired, but he seems to have been coming up in the polls recently and has been pushing a very strong line for freezing transport fares in London and doing more for policing which is striking a chord," said Dunleavy, "But he is the candidate who is behind."