Sensitive documents about a £1.3 billion Royal Navy “hunter killer” submarine were found abandoned in the toilets of a Wetherspoon pub, say reports.
The files were said to have been marked 'official sensitive' and carried details about the HMS Anson and were left in The Furness Railway in Cumbria.
The nuclear-powered vessel - part of the Astute-class programme - took nine-and-a-half years to build.
The documents reportedly showed the inner workings of the submarine and were used by submariners learning how to isolate and depressurise elements of its system.
The Royal Navy has said the papers were generic resources and did not contain any classified information.
A source told The Sun the pub was packed and the files marked 'official sensitive' were discovered lying on the floor of a toilet cubicle.
They said: “It was quite a lively night. The pub was full of people from the docks — military and civilian.
“I went into the toilet and the plans were lying on the floor of the cubicle with the lanyard.
“Anyone could have found them. It was lucky it wasn’t some deep cover Russian spy.”
The Furness Railway is a short distance from a BAE systems shipyard in Barrow-in-Furness, where the submarine has previously been pictured.
HMS Anson is the fifth of the new Astute-class attack submarines to join the Royal Navy fleet.
The vessels are capable of firing tomahawk missiles and described as the “largest, most advanced and most powerful attack submarines” ever used in the navy on its website.
A naval source said: “These documents enable submariners and contractors to understand how systems interact. They do not detail how they work, just that they exist.”
They added that the files only contained simplistic designs of the systems on board, without revealing how they work.
A Royal Navy spokesman said: “These are generic training documents that carry no classified information. However, we take all security matters extremely seriously and will investigate the circumstances of their discovery.”
