A personal intervention by Tony Blair has paved the way for Ken Livingstone's return to the Labour Party.

Labour's current candidate for London Mayor, Nicky Gavron, told the prime minister this week that "subject to terms and conditions" she is ready to stand down if Livingstone is allowed back.

She is understood to have agreed in principle to a deal under which she would become deputy mayor, during a 30-minute meeting with the prime minister in Downing Street on Tuesday afternoon.

When asked if Livingstone or Gavron would be a better mayor, Tony Blair told MPs yesterday: "I always support the Labour candidate."