
Top secret plans showing the designs for the Royal Navy ships which fought in the First World War have come to light a century after the only major sea battle of the war.

The detailed documents, showing the capital ships of the Grand Fleet, were found in a cardboard box lying in a corner of an attic in Sussex.

They are now set to be auctioned off as a historical curiosity - but at the time they were made they were incredibly sensitive, and could have spelled disaster if they had fallen into the hands of the Germans.

Plans: This document showing the interior of HMS Neptune was found in an attic in Sussex, hidden in a cardboard box

Secret: The cache of documents dating back to before the start of the First World War would once have been extremely sensitive

Historic: The plans cast light on ships involved in the Battle of Jutland, including Admiral Jellicoe's flagship Iron Duke

The eight draughtsman's drawings pre-date the Battle of Jutland, and reveal how ships' systems were built, including the mechanical weapons and torpedo bays.

They were discovered by chance when a couple were clearing out an elderly relative's loft at a home in Billingshurst, West Sussex.

Admiral Lord West, the former First Sea Lord, called for the plans to be saved for the nation because they could be our last link to the design of the vessels.

He said: 'I would have to study them in detail, but these plans could be of national importance and should therefore be in a museum.

'It's possible that they could be the only plans that still survive from these great ships.'

Detail: The 'fire control' plans for HMS Hercules and HMS Colossus would have helped seamen at the time

Unique: Admiral Lord West suggested that there may be no other documents which cast as much light on the ships as these

Weapons: This sketch gives details of how the deadly torpedoes were stored on board the Iron Duke

The sketches show the insides of the steam-powered ships involved at Jutland - including HMS Indefatigable, which was sunk minutes into the battle of the coast of Denmark in May 1916.

There are also designs for The Iron Duke, the flag ship of Admiral John Jellicoe, who was widely criticised for the heavy losses sustained at Jutland.

Britain lost more than 6,000 sailors and 14 ships, while just 2,500 Germans were killed - but the battle was later seen as a British victory because it set the stage for the country's ongoing naval supremacy.

Shipyards across the country would have used the top secret plans to build components, and the pictures bear stamps that date them to before the start of the war in 1914.

The hand annotated plans are for sections of the battleships Iron Duke, Hercules, Colossus, Indefatigable, Glorious, Dreadnought, Neptune and Bellerophon.

Helpful: Pictured are instructions to be followed during construction, left, and a pile of documents, right, concerning key ships

Finish product: This page of the plans shows photographs of Colossus and Hercules after their construction

Deadly: HMS Dreadnought's 12-inch guns are detailed in these documents found in the secret stash

Denise Kelly, of Bellmans Auctioneers of West Sussex, said: 'We don't really know where these documents came from and where they have been for so long, they were definitely not for public consumption.

'These scale drawings were top secret and were a huge part of history.

'As soon as we saw the names of the ships we knew they were very important, particularly with the links to the Battle of Jutland.

'It's a huge piece of history. You just don't see these things very often and they have appeared on the centenary of the battle of Jutland.

'To have one or two of these ships would be nice, but to have so many is just great.'

The Iron Duke plans are expected to fetch £100 and the other documents £200 when they go up for auction tomorrow in two separate lots.