Roll out the cognac barrels

Very old cognac you might think should be served in one of those big balloon glasses – and swirled round and round for all it is worth before a drop is drunk – so it comes as surprise to discover the most expert of cognac tasters sipping a 1965 vintage from the kind of elegant flutes one normally associates with sherry and old ladies.

Non, it seems this simple glass is the perfect size and shape from which to appreciate Hennessy, the world's best selling cognac. We're at Hennessy's Distillerie du Peu, in the countryside outside the town of Cognac, surrounded by gleaming antique copper distillation equipment. Cognac is basically wine twice distilled in copper pots, then sealed for at least two years in French oak barrels, and in the case of the rarer cognacs for a good deal longer.

Glass after glass of gold and amber cognac are passed around, and guests are told they they may spit out the contents between mouthfuls, but few do. "I wonder if we'll get to taste the Paradis," says one guest, referring to the finest of Hennessy blends , a concoction with elements over a century old, in a designer bottle that sells for upwards of €650. But we're not here for the Paradis. This party is all about Hennessy 250, a new cognac created to celebrate 250 years in business for the spirits house founded Irishman Richard Hennessy in the 1760s, and which is now part of the world's largest luxury goods group, LVMH (Louis Vuitton Moët Hennessy).

The Paris-based empire, which includes such brand names as Dior and Moët & Chandon, made sales of €30.6 billion in 2014, with Hennessy second only to Louis Vuitton in terms of profitability. The brand is flourishing under president and CEO Bernard Peillon, a father of six and marathon runner who has led growth for the past seven years, having previously revived the fortunes of Ruinart champagne. His vision for Hennessy is to see business doubling within 15 to 20 years.

As the day goes by in a blur of introductions, tastings and and wandering through cellars full of ancient barrels of the eaux de vie that go into Hennessy cognacs, we’re promised that the evening will reveal the new blend, and the ambitious plans for its worldwide launch.

In the meantime, we have an hour to kill in the town of Cognac, with its handsome townhouses and warehouses lining the Charente river. Even the most modest cafes on the main square have an impressive array of cognacs on display, while the Francois Premier hotel, where we are billeted for the night has a small residents' bar with shelves packed with elaborately designed and dimpled bottles.

There's no time to linger though, as we're due at Chai du Fondateur, a cellar lit by hundreds of glowing electric candles, where the Hennessy 250 barrels are resting. It's numbingly cold so we only linger long enough to be introduced to Yann Fillioux, the master blender of Hennessy and a member of the Fillioux family, generations of whom have worked alongside the Hennessy clan.

He is one of the most respected blenders in the world of cognac and next day we find out why. We're at Rue de la Richonne, the headquarters of Hennessy. A fleet of Mercedes sweep through a set of gates into a large courtyard in front of a grand cut- stone townhouse with steps leading up to the front door. This is home to the Grand Bureau, a room that's strictly off limits to the public. Here, between walls lined with shelves on which sit hundreds of numbered bottles, the tasting committee, led by Fillioux, meet every morning at 11am. For one hour they taste eaux de vie from different barrels and casks, deciding which should be blended together and for how long they should sit. The committee has seven members, all men. Women, says one committee member, off the record, are excellent tasters, often with more refined palates than men, but tasting dozens of spirits a day, he says, takes a toll on the body. "You have to be very strong," he says.

Hennessy 250 was born in the Grand Bureau, and is now being promoted on a world tour that started in Guangzhou, China, and will continue to Moscow, New York, Johannesburg, and will see the cognac celebrated by international artists in prestigious galleries. Export markets have always been key for the company, which tapped the US market in the 1780s and went half a globe to China in the 1870s. It has been exporting to Malaysia for around 100 years

It's all a far cry from the village of Ballymacmoy in Co Cork where Richard Hennessy was born in the 1720s, youngest son of Lord Ballymacmoy and so with little inheritance to look forward to. At 20 years of age, he took flight to France to fight with King Louis XV. Injured at the battled of Fontenoy, he later settled on the banks of the Charente River, and developed a cognac business. However, as Bill Linnane wrote recently in The Examiner, "It was Richard's son James who accelerated the expansion, forging links with the Martell Cognac dynasty through marriage and also being one of the first drink producers to begin trade with the Revolutionary Government, while also linking up with traders in London and New York in the 1800s." Later, the Hennessys joined forces with the Fillioux family and the partnership flourished.

Several members of the Hennessy family are still actively working with the brand, most notably Maurice Hennessy, its leading brand ambassador, who farms his own land in Cognac but who spends a great deal of time travelling the world promoting Hennessy. He's brilliant company, with a fund of anecdotes and recommendations that range from advice on how to the store truffles – among a heap of eggs, or tucked into a bag of rice – to the medicinal qualities of Hennessy – at the beginning of the Prohibition era, Hennessy was the only spirit sold in pharmacies with a doctor's prescription.

He also explains one of the reasons why rappers like cognac. Or at least why they favour Hennessy cognac. In 1951, he says, Hennessy was the first spirit to advertise in Ebony magazine, while in the late 1960s, the brand made the bold move of promoting African-American Herbert Douglas (bronze winner at the 1948 Olympic Games in London), to vice president, making him one of the first African American VPs in corporate America.

These days he spends a good deal of time in China and America, where Hennessy is hugely popular thanks to the revival of cocktail culture.

The family still has strong ties to Ireland, with Maurice's brother Frederick living in the ancestral home in Cork, where he recently welcomed 55 wine growers from Cognac as part of the 250 celebrations.

Tours of Hennessy Maison run daily from May to September and include tastings. Blending workshops are also available at 1 rue de la Richonne; Quai Maurice Hennessy; 16100 Cognac . Tel : +33 (0)5 45 35 72 68, see hennessy.com

* This article has been amended to attribute a quote from writer Bill Linnane that had appeared in the original piece unattributed