A Union Jack flag flown aboard one of Nelson's warships during the Battle of Trafalgar is to auction at Holt's in Norfolk, UK.
The lot is valued at £30,000-50,000 ($45,208-75,348) ahead of the sale in March next year, but is likely to sell for substantially more as one of only three surviving British flags from the battle.
The flag flew on the HMS Leviathan and was later given by Captain William Baytun to the Duke of Clarence - who would become King William IV.
The king then passed it on to the pilot of his royal yacht, who helped him win a race (and a bet) during the 1830s.
Since then it has been in the possession of the Cory family at their home in Penllyn Castle in south Wales.
Consignor Arthur Cory explained: "Ever since I was a small boy I have known about the flag from when my father showed it to me and told me where it was from.
"It was kept folded up in a damp cupboard in the old servants hall along with lots of other flags. I inherited it in 1981 and kept it in the same cupboard.
"It is always sad to sell these things but we have a bit of a roof problem and watertight roof is more important than a piece of history that isn't doing anything useful."
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