A spy pencil made by Cumberland Pencil Factory, on the site of Derwent Pencil Museum in Keswick, was valued at £400 on the Antiques Roadshow on Sunday (June 17).

The World War Two pencil, assessed by Mark Allum from the BBC, was brought in by a member of the public in a show filmed in Newcastle Civic Centre.

The owner of the pencil said: "I understand they were made during World War Two during the night time, when the factories were closed as a top secret instruction from the Government."

The pencils were specially created by Charles Fraser Smith in 1942 alongside the Cumberland Pencil Factory, and aimed to assist Lancaster Bomber pilots in their efforts or help prisoners-of-war escape German camps.

Miniature maps on tissue paper were inserted into the barrel at the end of the pencil detailing four different escape routes through Germany, Netherlands, Belgium and Switzerland. There was also a compass concealed within it. These were issued to the Royal airforce and sent to POW camps and played a vital role in the wartime escape network.

Dawn Walker, manager of the Derwent Pencil Museum, was shocked to see the pencil on the television and said:

"We knew how special these pencils were, but we never expected to see one of them on the Antiques Roadshow.

"It’s unknown how many are left in the world, due to the fact they were carried in one of the UK’s most recognisable aircraft during World War Two. I’m actually thrilled that there is another pencil in circulation."

The Derwent Pencil Museum has four 1942 originals on show in the Keswick attraction, including one pencil with a seventy-year-old map of Germany.

The pencils reveal their secret compartment and internal items – which were kept hidden from the public under the Official Secrets Act until 1975.

They were donated by surviving relatives of inventor Charles Fraser-Smith, thought to be Ian Fleming's inspiration for Q in the James Bond series. Charles called his spy inventions Q gadgets after the Q ships - warships disguised as freighters, which were deployed in the first World War.

Replica spy stationary sets were produced two years ago to celebrate Derwent Pencil Museum's heritage and role in the war effort and are available from the Derwent Pencil Museum, which is open every day from 9.30am to 5pm.