Philip Hammond faces the most ­difficult budget of any chancellor in recent decades because of Theresa May’s Tory minority government and a lack of economic flexibility

Tory whips have mounted a covert campaign to stop the Treasury announcing high-risk plans in the budget that could face defeat in parliament.

Conservative MPs told The Times that they were urged to put their name to private petitions seeking to relax the planning rules to allow more housebuilding. Lists of names were drawn up to show to the Treasury in an attempt to stop ideas that could result in a rebellion bringing down the budget in the Commons.

Philip Hammond faces the most difficult budget of any chancellor in recent decades because of the Tory minority government and lack of economic flexibility.

The Treasury has made clear that reforms to encourage housing development are a key part of tomorrow’s budget but a reluctance by