BORIS Johnson was elected Mayor of London tonight, capping a catastrophic day for Labour in the local elections.

The Conservative candidate seized City Hall from Labour's two-term incumbent Ken Livingstone with Liberal Democrat Brian Paddick in third place.

Mr Johnson polled 1,168,738 votes to Mr Livingstone's 1,028,966.

The result heaped further pressure on Prime Minister Gordon Brown after his party plunged to its worst council election results in four decades.