The UK government is set to wave through the £4bn takeover of Cobham by Advent International after the US buyout group agreed to strengthen security arrangements around sensitive sites and inform the Ministry of Defence if it plans to sell all or part of the UK aerospace and defence supplier.

The ruling comes three weeks after Andrea Leadsom, Britain’s business minister, instructed the Competition and Markets Authority to investigate whether the sale of the air-to-air refuelling equipment maker posed a national security threat.