One of the experts noted a whiff of mushrooms, a second thought he detected a hint of white truffles, while a third was struck by the flavour of honey and gingerbread.

But on one thing they could all agree: it was an historic event as the world’s oldest bottle of champagne was opened — 184 years after it had been sealed and stored away.

“It’s not surprising that opinions differed about it,” said Olivier Cavil, of Perrier-Jouët, the champagne house that produced the bottle in 1825, when George IV was on the British throne. “It is very difficult to be objective when you are submerged in emotions and this was a very emotional occasion indeed.”

As Hervé Deschamps, head of the Perrier-Jouët cellar, eased out the cork in Rheims, northern France, his blood pressure mounted. “It was very stressful,” he said. “I was worried that the cork would break because it had never been changed. And I was afraid the champagne would be undrinkable. But luckily, it was drinkable.”

Mr Cavil added: “Although there was only a hint of bubbles left it was perfectly fresh, the colour was fine and it resembled a very great chablis, with a note of white truffles and chocolate.”

The 1825 bottle was opened along with 19 other Perrier-Jouët vintages — four from the 19th century, fourteen from the 20th and one from the 21st — at a ceremony to which the champagne house had invited 12 experts to sample what it called “liquid history”.

Perrier-Jouët said that it had laid on la dégustation to announce its latest vintage, from 2002, with a demonstration that good champagne can be kept for decades in the right conditions. “The bottles from the first half of the 19th century were more or less flat,” Mr Cavil said. “But the 1874 was still sparkling. The bubbles lasted for 45 seconds after it had been opened.”

Bubbles or no, the 1825 had the tasters in raptures. One of them, Serena Sutcliffe, head of wine at Sotheby’s, compared it to “mince pies cooking at Christmas time — it was very addictive and very special”.

Michel Bettane, France’s most celebrated wine critic, said the tasting this month was an experience he would not forget. “It’s the sort of thing which happens once in a lifetime,” he told The Times. “The 1825 was a very interesting wine. There were flavours of mushrooms, woods and a bit of honey.” However, he preferred the 1911 and 1952, which were a “great lesson” for champagne producers.

Bernard Burtschy, wine writer for Le Figaro, described the 1825 as “generous with an intense nose. There was a taste of heather honey, of gingerbread, of lemon confit, of mushrooms and of the dead leaves which are the grey hairs of a wine which has aged.”

The oldest wines had been stored in the same spot in Perrier-Jouët’s cellars, 70ft underground at a constant temperature of 11C (52F). Perrier-Jouët has two more 1825 bottles in the cellar. “And we’re not opening them in the near future,” Mr Cavil said.

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