Whitehall's indifference to the defence and national security implications of private equity and overseas bids in Britain's aerospace and engineering sector is disturbing. In spite of a heavily redacted national security report on the sale of aerospace group Cobham to Advent, warning of its importance to UK defences, it was sold off with few safeguards. At the time of the proposed 2012 merger of the UK's defence industry leader BAE with Europe's Airbus it took an intervention from Angela Merkel, concerned about production in Germany, to scupper the transaction while Britain sat on its hands. Whitehall's indifference to the defence and national security implications of private equity and overseas bids in Britain's aerospace and engineering sector is disturbing, says Alex Brummer