David Cameron will on Wednesday face down pressure from his Eurosceptic party to offer a referendum on European Union’s Lisbon treaty. The Tory leader will instead pledge to bring control of social and employment policy back to Westminster in his party’s general election manifesto.

In a speech on Wednesday afternoon setting out his party’s contentious new policy, Mr Cameron is also expected to reiterate the Tories’ commitments never to join the euro and to create a legal requirement to offer a referendum on any future treaty that transfers power to Brussels.