SoftBank has pledged to legally guarantee that ARM Holdings’ headquarters will remain in the UK after its £24bn takeover of the British microchip designer.

The Japanese company had said it intended to maintain ARM’s Cambridge base when it announced one of the biggest foreign acquisitions in British corporate history last month, but on Wednesday upgraded this to a binding pledge.

The pledge, which comes after discussions with the Government in recent weeks, will be the first under new Takeover Panel rules designed to prevent broken promises after foreign takeovers.

When it announced the deal in mid-July, SoftBank said that its pledge to double ARM's 1,700 employees in the UK would be legally binding.