The new American owners of UK defence giant Cobham vowed to keep jobs and investment in Britain to obtain government approval for the controversial £4bn takeover.
Cobham revealed that private equity firm Advent International made a series of pledges including maintaining a UK headquarters.
Advent also said it would continue funding research and development at its Dorset offices and keep using the Cobham name.
Cobham’s contracts with the Ministry of Defence and the Home Office will remain in the UK and any future sales of parts of the business must be cleared by the two government departments.
Advent said it had a “commitment not to restructure the UK operating companies’ capacity in a way that would result in some, or all, of the relevant activities being developed and/or supplied from outside the UK without the written approval of the relevant [government] department”.
The legally binding commitments helped persuade the government to approve the deal, which had been held up over national security fears.
Andrea Leadsom, the business secretary, was accused of attempting to avoid scrutiny by confirming the deal would go ahead in a press release issued late on Friday night.
Lady Nadine Cobham, the daughter-in-law of the company’s founder Sir Alan Cobham, said: “This is a deeply disappointing announcement and one cynically timed to avoid scrutiny on the weekend before Christmas.
“In one of its first major economic decisions, the government is not taking back control so much as handing it away.
“In Cobham we stand to lose yet another great British defence manufacturer to foreign ownership, through a takeover that would never have been approved by the Americans, French or Japanese, all of whom have taken steps recently to raise protections for their own defence sectors.”
Shareholders voted for the deal in August but it was then subject to a review by the competition watchdog. It is now expected to conclude on 17 January.
Shonnel Malani, a partner at Advent, said: “Advent takes its custodianship of Cobham seriously, and we are confident the transaction and undertakings being given on national security, jobs and future investment, provide important long-term assurances for both Cobham’s employees and customers, particularly in the UK and also globally.”
Prime minister Boris Johnson defended the sale over the weekend.
He said: “I think it’s very important that we should have an open and dynamic market economy.
“A lot of checks have been gone through to make sure that in that particular case all the security issues that might be raised can be satisfied and the UK will continue to be a very, very creative and dynamic contributor to that section of industry and all others.”
The business, which is a world leader in air-to-air refuelling systems, was founded in 1934 as Flight Refuelling Ltd, before listing on the stock market in 1985.