Boris Johnson angered David Cameron’s inner circle so much with his performance at the Conservative Party conference that one member sent him a text message with a threat taken from The Godfather.

The two most powerful Tory politicians in Britain continue to insist that they share a relationship so close that it is characterised by Mr Johnson as “glutinous harmony”.

But those relations will become harder today after an admission by a member of Mr Cameron’s inner circle that he sent a classic Mafia threat to the Mayor of London.

Nick Boles, who is in charge of drawing up Conservative plans for government, quoted from The Godfather during the row, which was provoked by Mr Johnson’s support of a referendum on the Lisbon treaty.

Having returned to London from the conference in Manchester on October 5, Mr Johnson received the Italian threat, “La vendetta è un piatto che va mangiato freddo”, by text message in the early hours of Tuesday. It translates as: “Revenge is a dish best eaten cold.”

“Given the hour it was sent, it was decided it could be safely ignored,” a friend of Mr Johnson said. Rumours of an abusive text surfaced during the conference although the sender’s identity was a mystery. But Mr Boles admitted that he sent the message.

“Boris and I are old friends who have worked closely together for a number of years,” he said. “Boris is not the only one who can express himself in ornate language. I would also point out that I began this particular message by saying that I was one of his biggest fans.” He added: “I know Boris will be disappointed but you wouldn’t believe how hard it is to get hold of a horse’s head these days.”

Mr Boles said that Mr Cameron, George Osborne, the Shadow Chancellor, and Andy Coulson, the director of communications, did not know about the text. The mayor’s spokesman said that the message had not come from anyone in Mr Cameron’s office. A senior Tory source said: “This was definitely Nick freelancing. David knew nothing about it.”

Mr Boles, a director of the implementation team, is an influential figure. He will, for example, have a say in whether the Conservatives commit funds to the Crossrail project. Mr Johnson has failed to win an undertaking from Mr Cameron that the key London transport project will be protected from cuts. The Conservative candidate for Grantham is a former director of the Policy Exchange think-tank and was a leading voice in the Tories’ modernising wing. He campaigned to be selected as the party’s London mayoral candidate before pulling out on health grounds. He later helped Mr Johnson’s campaign.

Frustration with Mr Johnson among Mr Cameron’s aides is likely to boil over again if he makes a further intervention on Europe. With the Czech President Vaclav Klaus the last remaining obstacle to ratification, and indicating that he is about to give up his opposition, Mr Cameron is facing one of the most important decisions of his leadership.

It appears likely that he will disappoint those in his party who want him to commit himself to a post-ratification referendum. But he isaware that however he clarifies his promise not to “let matters rest there” if Lisbon is implemented, it will leave plenty of opportunities for vengeful enemies.

Behind the Story: A cliche best served cold

In the Iliad, revenge was said to taste like honey. Between the epic conflict of two civilisations and the smaller animosity between two senior Conservatives, expressed in threatening late-night text messages, lies a long line of serving suggestions for vengeance.

Almost from the beginning, vengeance was something to be consumed. The Book of Deuteronomy describes the revenge God shall wreak upon His enemies: “My sword shall devour flesh.” In 16th-century drama, Shakespeare’s Shylock seeks to “feed my vengeance”. How should this vengeance be consumed? Cervantes thought it was “not good in cold blood”.

By the 19th century, on the other hand, it was proverbial that “revenge is a dish that can be eaten cold”. A century later the words could issue as easily from the mouth of a Sicilian mobster as from a bloodthirsty Klingon in Star Trek. They could even be used by a Conservative strategist.

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