The bottle of Coutanseaux 1767 is said to be worth about £100,000. Guests of the hotel can purchase a 50ml measure for £7,000.
According to The Wellesley the ancient bottle was discovered in a cellar in France by a Cognac collector and has been had its authenticity verified.
Coutanseaux 1767 was distilled in the same year as Mozart’s first opera and at a time when George III was on the throne of England.
The Wellesley’s collection also includes Cognacs from 1789, 1793 and a Boutelleau from 1800.
Giuseppe Ruo, director of food & beverage at The Wellesley says: “Cognac is one of the passions of The Wellesley, we are constantly in search of the finest and most unique vintages in the world to offer to our discerning guests.
“We are very excited to welcome Cognac enthusiasts to experience this outstanding addition to our distinguished collection.”