An astonishing working model of a guillotine made by Napoleonic prisoners of war in Britain 200 years ago has been discovered in Dorset.

The incredibly rare, 20 inch-high replica was crafted by an inmate using animal bone that was probably stolen from kitchen bins.

It was discovered by an expert doing a routine valuation in a house near Dorchester and is now set to fetch £8,000 at auction.

The model shows a platform lined with soldiers and a set of steps up to the guillotine itself.

Other soldiers surround the blade and a decapitated body lies beneath it.

The macabre model is intricately carved and the blade goes up and down – even the soldiers who are holding swords have moving arms.

It was probably made between 1805 and 1815 and has been kept in excellent condition by the family that has owned it since the 19th century.

The mostly French prisoners included many craftsmen who created some incredible furniture and models that they sold through local traders.

While incarcerated, often for years in prisons such as those at Welshpool and Montgommery in Wales and Plymouth, the prisoners had plenty of time Amy Brenan, from Duke’s auction house in Dorchester, said the family who owned it had no idea what it was.

She said: “With little contact outside the prisoner of war camps, prisoners were forced to improvise. Cheap materials like straw and scrap wood were easy to find and prisoners were able to use skills learnt in their trades outside the camp to produce high quality objects such as woven straw-work boxes.

“The working guillotine model being offered for sale is made from bone, most probably sheep bone, derived from the rubbish bins of the camp kitchens.

“The guillotine was a vivid symbol during the French revolution and a number of these models were actually working examples such as this one.

“The guillotine blade moves up and down and the soldiers each have reticulated arms so the swords they are holding can move up and down.

“Each figure is carefully highlighted in black and red to denote facial expressions and the uniforms of the soldiers.

“Napoleonic prisoner of war models made from bone and ivory are hard to come by.

“Many designs such as the model battle ships, spinning jennies and guillotines are so intricate that they disintegrate overtime and this makes any surviving examples extremely rare.

“The sheer skill in creating a working model of the guillotine coupled with its social significance at the time, has made the guillotine models particularly desirable.

“I was doing a routine valuation in a house when I saw the model.

“The family had no idea what it was.”

The guillotine will be sold at Duke’s on February 9.