Politics: Why a European referendum is now almost certain

The Romford Pledge might not have the same ring to it as the Tamworth Manifesto. But Boris Johnson’s decision while campaigning last month to sign up to the campaign for an in/out referendum on EU membership could be a key moment in the history of the Conservative party — the moment when the party’s balance of power tipped decisively in favour of a referendum.

As with so many of Boris’s actions, it is hard to know whether his pledge was spontaneous or a calculated move. Certainly, the Mayor hesitated before signing. Then, according to those present, the seat’s Eurosceptic Tory MP, Andrew Rosindell, told him it wasn’t party policy to sign — and that appeared to make up his mind. But Boris’s signature on the People’s Pledge has changed the dynamics of the Tory debate about Europe. When he returns to the Commons, his standing as the only Tory since Margaret Thatcher to win a personal mandate for high office twice will demand a post in Cabinet.