The Government has launched a probe into how sensitive documents detailing the Prime Minister’s schedule on an official visit were found on a train and published by the Daily Mirror.
As well as setting out transport arrangements for a visit to the North West, the papers included the address of a hotel Mrs May was booked in to work from during the afternoon.
The documents, discovered in the first class train carriage of a train heading for Edinburgh on the day of the visit, were handed to the newspaper by a member of the public.
Former royal bodyguard Inspector Ken Wharfe told the newspaper that leaving travel documents on a train was “inexcusable” and a “serious security breach”.
He said: “These papers give a detailed -assessment of her movements. Had such information reached potential terrorists it could serve to confirm their plans.”
The Mirror said the papers included briefing notes for Teresa May on how to deal with hostile questions from reporters.
A government spokesman said: “We have been made aware of claims around a government document and will investigate accordingly.”