A RARE Carlisle 'seige' coin used during the English Civil War is heading to auction.

The Charles I shilling, minted in 1645, is expected to fetch between £8,000 to £12,000.

This type of currency, known as 'siege coins', was used as emergency money during the Civil War to pay soldiers and conduct daily transactions.

Isolated from the main Royalist forces, coins were in limited supply for many towns and therefore any silver such as church plate, flagons, private flatware or whatever they could lay their hands on, was turned into coin.

The shilling, and others like it, were struck often bearing the letters OBS, standing for the Latin word obsessum (besieged) or perhaps obsidio (siege).

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Carlisle, a key Royalist stronghold in northern England, was besieged for eight months following Royalist defeat at Marston Moor in Yorkshire.

The garrison, led by Sir Thomas Glenham, defended the fortress amidst severe shortages of food and supplies.

The siege ended in June 1645 when the weakened defenders negotiated terms of surrender.

They were permitted to march away with their weapons to join their King.

The shilling is part of the Frank Waley Collection of Hammered Silver and Milled Gold, which will be auctioned at Baldwin’s Auction House in London on December 11.