Lord Adonis, the transport secretary, has watered down plans proposed by his predecessor, Geoff Hoon, to take over the running of Heathrow and London’s other main airports if their owners ran into financial problems.

In a boost for BAA, Heathrow’s debt-laden owner, the Department for Transport said on Tuesday it was dropping a plan put forward earlier this year to set up a “special administration regime” to make sure airports stay open in the event of insolvency.