Advisers say a flawed attempt by Chancellor George Osborne to clamp down on tax avoidance will force him into a new strategy swerve, following four Budget U-turns: on church improvements, charitable giving, hot pasties and caravans.

The General Anti-Avoidance Rule - part of Osborne's war on tax abuse and designed to pull in £5bn a year - is the latest idea to hit trouble even at its consultation stage.