EU referendum: How a Brexit could benefit Theresa May

If Boris Johnson joined the Leave the EU campaign, he would, of course, become its leader

Theresa May would become the most powerful member of the Leave campaign (Getty )

If Boris Johnson won’t come out against Britain’s membership of the European Union, then Theresa May must be likely to. That is the Namierite analysis of the way the referendum interacts with the Conservative leadership election – two events that are going to happen but for which precise dates have not yet been set.

Lewis Namier’s great work was The Structure of Politics at the Accession of George III, published in 1929, in which he argued that politics in the 18th century was explained by the interests of individual MPs and peers, rather than by principle or party. If we look at the structure of politics, at what the Chancellor would like to be the accession of another George, we can see how one of his rivals for the succession is likely to end up leading the campaign to take us out of the EU.

After Johnson’s speech to the Conservative Party conference last month, in which he cleverly used the irresponsibility of being out of office to set out impossible demands for David Cameron’s renegotiation, there was a flurry of speculation that he might join the Leave campaign. “It should be up to this Parliament and this country – not to Jean-Claude Juncker – to decide if too many people are coming here,” he said, knowing full well that the Prime Minister is not even asking for such curbs on the free movement of EU workers, because he knows he couldn’t get them.

If Johnson joined the Leave campaign he would, of course, become its leader – given that its best-known active politician is Douglas Carswell, the lone Ukip MP, and that its highest-ranking one is Owen Paterson, who resigned as Environment Secretary last year.

Boris said that it should down to Britain to decide how many immigrants the UK takes rather than the EU (Getty)

I don’t think Johnson will do it in the end. Look to his self-interest. I don’t know what Cabinet position Cameron might have hinted at in text messages discussing how Johnson might join the Government after his term as Mayor of London expires in May, but he can expect a big job. Not least because Cameron, who has his interests too, wants to keep Johnson away from the Leave campaign.

The most important sub-structure of Tory politics, however, is the rules for the leadership election. Labour MPs often say privately that the Tory party’s rules are far better than theirs. They look enviously at a system that would give them back some of the power they lost in Ed Miliband’s accidental revolution. Under the Tory rules, the MPs vote repeatedly in an eliminating ballot until there are two candidates left. Those two names are then put to the party members to make the final choice.

This produced a curious result in 2001. Michael Portillo led in the first two rounds of voting, before slipping one vote behind Iain Duncan Smith in round three, and six votes behind Kenneth Clarke, who went on to lose to Duncan Smith by 61 per cent to 39 per cent among members.

It is this system that gives Theresa May, whose job as Home Secretary may or may not be offered to Johnson, the incentive to join the Leave campaign. George Osborne is most likely to make it to the final two when MPs vote. He has the blessing of a Prime Minister who won an election that many Tory MPs had written off, and he has created a powerhouse of Namierite advancement. Many Tory MPs looking to their interests know that Osborne’s approval is important to their prospects of ministerial promotion.

There are other MPs who feel that the Chancellor has failed to recognise their potential, and who look to Johnson as a possible alternative under whom their talents would be put at the service of the British people.

There are not so many MPs, however, who think that their careers would be best served by the succession of Theresa May to the leadership – or of Nicky Morgan or Sajid Javid for that matter.

Thus Johnson does not need to play the anti-EU trump card to get into the final two on the leadership ballot. He is not exactly popular among Tory MPs, but he has been working on them and they recognise his appeal with the public. If he were to lead the Leave campaign and lose the referendum, his hopes of becoming PM would be over. Better to stay in with the stay-inners and posture for the sceptics.

May is in a different position. She will have held the highest office apart from prime minister that she could expect. She would find it hard to make the final two unless she shakes up the race. For her, the trump card is worth playing. If the British people vote to leave the EU, a cabinet minister who had advocated leaving would be very likely to take the top job. Not least because last week’s ConservativeHome survey of party members found that 75 per cent of them expect to vote to leave the EU in the referendum.

You will notice that I haven’t mentioned the arguments for or against EU membership, or the beliefs of the players. If Theresa May looks to her self-interest, leading the Leave campaign is a risk worth taking.

Twitter.com/@JohnRentoul