Johnson says crime has become “scourge” of London

London mayoral elect Boris Johnson says a fightback against the “scourge” of crime will be his priority at City Hall.

The Conservative candidate, who beat incumbent Ken Livingstone in the mayoral polls held on Thursday, signed the declaration of acceptance at City Hall this afternoon.

Hours after his victory, which was announced shortly after midnight on Saturday, a 15-year-old boy was stabbed to death in the stairwell of a block of flats in Southwark.

Mr Johnson’s speech after he signed on to become mayor promised to make crime a priority for his administration.

“This problem of kids growing up without boundaries, of getting lost in tragic, catastrophic, self-destructive choices, is the number one issue that we face in this city,” he said.

Mr Johnson, who officially becomes mayor on Monday and is likely to stand down from being MP of Henley and trigger a by-election, added: “I do think there’s a vital necessity to drive out so-called minor crime and disorder as a way of driving out more serious crime.

“I think it’s within the power of all of us to make a huge difference to this if we get the policies right.”

After his speech the mayor-elect left for talks with Metropolitan police commissioner Sir Ian Blair, London fire brigade commissioner Ron Dobson and London transport commissioner Peter Hendy.

Mr Johson’s party leader David Cameron has already hailed his “remarkable victory”, which came as the Tories trounced Labour in local elections across England and Wales.

“Britain is crying out for real change and it is the Conservative party – modernised and united – that is winning the battle of ideas,” he said

“We’ve shown there is an alternative. We must now prove it. But I believe that my party – the Conservative party – is ready to step up for Britain.”

Mr Johnson has also been praised by the Confederation of British Industry (CBI), with its director general Richard Lambert claiming he would bring “vigour and enthusiasm” to the mayor’s office.

“It is important the mayor continues to protect and promote the city’s strengths, as well as address its weaknesses, particularly skills, infrastructure and transport,” Mr Lambert added.