Denis Staunton: David Cameron shows appetite for battle ahead

David Cameron's savaging of Boris Johnson yesterday offered a thrilling start to four months of Conservative civil war ahead of the referendum on Britain's EU membership in June. With its sly allusion to the London mayor's disorderly personal life and its questioning of his motives in joining the Leave campaign, the prime minister's attack was effective, precise and deeply personal.

By humiliating Johnson in public, Cameron may have hoped to undermine the impact of his fellow Etonian's support for the Leave campaign. But there was another political purpose – to choke off any idea that a vote to leave the EU could be followed by a further negotiation and a second referendum.

Johnson has in the past argued that voting to leave the EU could put Britain in a stronger position to renegotiate the terms of its membership, a theme he returned to in the Daily Telegraph yesterday.

“There is only one way to get the change we need, and that is to vote to go, because all EU history shows that they only really listen to a population when it says No . . . It is time to seek a new relationship, in which we manage to extricate ourselves from most of the supranational elements,” he wrote.

Second referendum

The idea of a second referendum appeals to some Leave campaigners as a way to overcome their biggest problem, the fear that leaving the EU is too risky.

Dominic Cummings

, campaign director for Vote Leave and a former adviser to

Michael Gove

, outlined the case for such a strategy in a blog post last June.

“This approach would enable No to build a coalition between a) those who think we should just leave (about a third) and b) those who dislike the EU but are worried about leaving (about a third) and who may be persuaded that ‘Cameron’s deal is bad and we should try to get a better one but the only way to force this is to vote No’,” he wrote.

Scaremongering

Belgium’s prime minister,

Charles Michel

, wanted last week’s EU summit to state in its conclusions that there could be no second renegotiation for Britain but he failed to win the support of other leaders. Article 50 of the EU Treaty says that a member state which decides to leave the EU should notify the

European Council

, which will then begin a negotiation about the terms of the country’s exit. If no agreement has been reached within two years, “the Treaties shall cease to apply to the State in question”, meaning it will no longer be in the EU.

Despite warnings of the negative impact of the scaremongering known as “Project Fear” during Scotland’s independence referendum, Cameron knows that fear of the unknown is among the most persuasive reasons for staying in the EU. Cameron said yesterday that he would immediately invoke article 50 if Britain voted to leave, but it is highly doubtful he would himself survive such a vote.

The beginning of the referendum campaign has been shakier than the prime minister can have hoped, with half of Conservative MPs, including a quarter of his cabinet, planning to campaign for a Brexit.

With his combative performance in the Commons yesterday, Cameron showed that he has an appetite for the fight ahead, and that he is prepared to be brutal with his adversaries.