Downing Street has said David Cameron wishes Baroness Thatcher "a speedy recovery".
Former Prime Minister Margaret Thatcher is in hospital recovering from an operation to remove a bladder growth.
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A robot was sent to the scene as police closed the motorway in both directions between Northampton and Milton Keynes.
Mostly dry after a misty start in places
A police officer has suffered potentially life threatening injuries after being assaulted in Doncaster.