When David Cameron said he was the “heir to Blair”, he didn’t realise that he was doing a deal like that struck by Jafar, the Grand Vizier of Agrabah in Aladdin. Jafar is the baddie who had three wishes and used one of them to become a genie himself, with “phenomenal cosmic powers”, but who was then trapped in a lamp, the price that he had to pay.

Cameron copied “the Master”, as he used to call him, and acquired some of Tony Blair’s phenomenal electoral powers – winning an election everyone expected him to lose – but he too has to pay a price. Like Blair, he is going to be trapped for ever in his own party’s disapproval.

As James Forsyth of The Spectator pointed out recently, the EU referendum is Cameron’s Iraq. So the Prime Minister is the heir to Blair in two ways. He has delivered his party into government for at least 10 years – but his party is the opposite of grateful.

Cameron’s unpopularity with his own is, as yet, nothing like the full carnival of loathing with which the Labour Party celebrates its former leader. That took 13 years to mature after the Iraq war, and the crucial event in breaking Cameron’s reputation with the members of his own party hasn’t even happened yet. But in six weeks’ time, if the British people vote to stay in the European Union, the great betrayal thesis will start to curdle into proper animosity.

You can tell that the Leavers are preparing for defeat. The late night outburst against ITV and Robert Peston, its political editor, by Dominic Cummings, the director of the Leave campaign, on Wednesday was a classic of the paranoid worldview. Cummings is a brilliant and original thinker who used to be Michael Gove’s special adviser at the Department for Education, but his claim that Peston was part of the In campaign, and that ITV had better look out because “the people in No 10 won’t be there for long”, made the official Leave campaign look ridiculous.

The parallels with the conspiracy theories of the less reality-based supporters of Scottish independence are uncanny. In the Scottish referendum, the SNP campaigned against “BBC bias” – and against Nick Robinson, then the BBC’s political editor, in person.

If the Leave campaign loses the referendum, the mythology of treachery will soon be complete. The Leavers will need no Chilcot inquiry to establish the causes of their defeat. Media bias, an establishment stitch-up and dossier-loads of so-called facts sexed up by spin doctors in No 10 will be to blame.

Friday’s report from the International Monetary Fund, warning of a “technical recession” if Britain leaves the EU, could be the “45 minutes” of the conspiracy theory of a stolen referendum. Already, sharp-eyed observers have noted that the Bank of England, in its warning of the consequences of Brexit on Thursday, used the same phrase, “technical recession”. The technical definition of a recession being two successive quarters of negative growth (or shrinkth, as it should be called). Suspicious, eh?

Far more than Iraq, which, people forget, was supported by conventional opinion at the time, Britain's EU membership is overwhelmingly backed by all sources of authority. Not just the IMF and the Bank of England, but the Treasury, the leaderships of all parties except Ukip, and by Barack Obama, Hillary Clinton and the Pope.

Far from meaning that the Leavers will accept defeat with good grace, this is likely to intensify the feeling that the Remainers triumphed as the result of an elite conspiracy against the rough-hewn good sense of the British people.

Which might not matter to Cameron, except that the membership of his own party are predominantly Leavers. “Their hearts beat in that direction,” as I’m told he said recently. A YouGov poll after his renegotiation found that 59 per cent of them intended to vote Leave.

If that is how Tory members divide on 23 June – and it could easily be higher – they are not going to forgive Cameron easily for selling the country down the Rhine, or whichever river Brussels is on (the Zenne or Senne).

That is why Boris Johnson is in such a strong position to succeed Cameron, whether the referendum is won or lost. Half of Tory MPs, who draw up the shortlist of two candidates, are Outers, and then the Eurosceptic party members make the final choice.

And that is why, even if he wins the referendum, Cameron will find that governing is like “driving with the handbrake on”, as Blair described his final years. Blair was talking about the effect of Gordon Brown on him, but Brown had that leverage only because Iraq had broken Blair’s support in the wider Labour Party. Cameron will find that Johnson, whatever post he holds in the ironically named reconciliation reshuffle after the referendum, will have the same effect on his government.