The remains of a World War II carrier pigeon - still bearing a secret coded message - have been found in the chimney of a house in England.

A quarter of a million pigeons were used on on active service during the War, flying messages in little canisters strapped to their legs across enemy lines.

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Some were also carried in bombers to be released in case of a crash.

But one pigeon never made it home.

Surrey resident David Martin found the bird's bones in his chimney when he was renovating his fireplace.

"About three handfuls of rubbish later, down came the leg with the red capsule on with a message," he said.

"You had to unscrew it and on a piece of paper, cigarette paper thin, was the secret message."

The capsule is the type used by spies who worked in occupied Europe.

The 70-year-old message was written by a Sergeant W Stott and is in code - which points to one destination.

Only about a dozen pigeons were based at the top secret Bletchley Park where Britain's brightest code breakers lived and worked.

But Colin Hill from the Bletchley Park pigeon exhibition cannot make sense of the code.

"All the messages that we've ever looked at have always been longhand, you know, that made two of us really sit and think that there is something a little bit special about this one," he said.

Seven decades after the pigeon fell from his metaphorical perch down the fireplace, the secret remains intact.

But modern day code breakers from the Government Communications Headquarters are on the case.

If they can crack it, there is hope that the leg and the canister may at least shed light on a fragment of wartime history.