BORIS Johnson yesterday compared Nicola Sturgeon and the SNP to a mass baby-killer, thieves, foxes, anti-alcohol campaigners, weevils, scorpions and the man known as the “Dread of the World”. The party were, Johnson said, “lefties on steroids” who were intent on “wrecking the country” with the First Minister as Lady Macbeth to Ed Miliband’s King of Scotland.

The Mayor of London, and the favourite to replace David Cameron as leader of the Conservative Party, wrote in his Telegraph column: “You wouldn’t get Herod to run a baby farm, would you? It would not normally occur to you to interview a convicted jewel thief for the post of custodian of the Tower of London.”

He continued: “You would not dream of asking a fox to look after the henhouse or a temperance campaigner to run a brewery or Attila the Hun to work as a doorkeeper for the Roman senate – and no one in their right mind would enter into a contract with a bunch of voracious weevils to protect the lovely old timbers in the tower of the local church. Would they?”

During the day Johnson’s colleague on the Telegraph Iain Martin also tweeted that the manifesto launch was akin to the Nuremberg rallies held by the Nazis.

Keeping with the Second World War theme, Ukip leader Nigel Farage accused Labour, the Conservatives and Liberal Democrats of “outright appeasement” in the face of the SNP.

Piers Morgan, meanwhile, called her a “mini-Godzilla”.

The First Minister was asked about Johnson’s remarks during the SNP manifesto launch. “If he did say that, then that is an entirely offensive comment”, she said, “and I think it will be treated as that, not just by people in Scotland but across the UK. In my experience, ordinary people the length and breadth of the UK do not see Scotland that way at all and do not see the SNP in that way at all.”