A centuries-old Irish military helmet which may be the 'only one in the world' is set for auction after being found on a hat shelf in a Twickenham home.

Antiques experts said they were stunned to spot a rare, late 18th century Tarleton-pattern helmet made for the 'Kinnelea & Kerricurrihy Cavalry'.

The flamboyant headwear 'worthy of a museum' was tucked away hidden among other hats on a shelf at a property in Twickenham.

After remaining in the same family since the 1780s, it is now set for auction this weekend (Sat) at Hansons London with a guide price of £300-£500 .

However, it is expected to fetch much more as auction experts believe there may not be another one like it in the world.

Chris Kirkham, associate director at Hansons London, spotted the military antique while collecting items consigned to auction.

He said the striking headwear caught his eye with its distinctive side plume, gilt trim, leopard skin band and shaggy black bearskin crest.

It may have been worn by soldiers any time after the American Revolutionary War (1775-1783) up until the end of the Napoleonic Wars in 1815.

He said: "I noticed the leopard banding and unusual style of the hat and immediately realised it was 18th century and significant due to the Irish cavalry connection.

"It's such a rare survivor, perhaps the only one of its kind in the world.

"It's even more surprising that it's remained in the same family since the 1780s. It's a museum piece really.

"There can be very few, if any, identical examples still in existence.

"The owner was unaware of its historical significance. It was an ancestral heirloom."

The helmet is named after British general and Liverpool Whig politician Sir Banastre Tarleton (1754-1833).

He volunteered to fight in the American War of Independence at the age of 21 in 1775.

During the conflict he made the Tarleton helmet popular. English portrait artist Sir Joshua Reynolds even painted Tarleton wearing a Tarleton helmet.

Chris added: "The hat was worn by all ranks in the British Legion, an elite British provincial regiment led by Tarleton which was established during the American Revolutionary War (1775-1783).

"Royal Horse Artillery troops wore the helmet until the end of the Napoleonic Wars.

"It was also the headgear of choice for light dragoon regiments from about 1796 to 1812."