"The old joke about the family who used to own this house is that they hunted and fished five days a week – but had weekends off,” Michael Flatley says in his smooth Irish-American brogue. “I love that old style of living.” Though he neither hunts nor fishes, you can see what he means about that long-lost life of leisure and pleasure.

We are standing on the sweeping lawns of Castlehyde, Flatley’s mansion in Co Cork. Up the gentle slope, the Georgian facade presents a vista of perfect symmetry, tucked in below a cliff topped by the ruins of a castle that dates from the 13th century, when the estate was the stronghold of the Maloney clan.

“I’m a workaholic, but I love being here,” says the showman whose high-octane interpretation of traditional Irish dancing has earned him an estimated £377m since his performance with Riverdance during the interval of the Eurovision Song Contest in 1994. “I get an awful lot done – my office is here.”

Below us, the Blackwater River ripples through the 150-acre estate. Flatley’s sweeping gestures indicate the 1½ miles of river frontage, where he can patrol, mobile to his ear, keeping tabs on business and taking in views of the opposite bank, where green meadows rise to wooded hillsides.

Born to Irish immigrants in one of the roughest parts of Chicago, Flatley, 49, took his first dance lessons at the age of 11. After a stint as a boxer, he made his name touring with the Chieftains in the 1980s. He now presides over a global franchise of shows such as Lord of the Dance – seen by 50m people in 60 countries – and Celtic Tiger. Not to mention all the DVD sales.

Currently a few pounds above his dancing weight, with a smooth Caramac-coloured tan and discreet blond highlights, Flatley has only recently relaxed his whirlwind schedule sufficiently to spend extended periods here. A mystery virus laid him low for a while last year, but the better reasons for staying home are his new wife, Niamh, one of his star dancers, whom he married a year ago, and their son, Michael, born in April.

Since buying Castlehyde in 1999 for £2.2m, Flatley has transformed the place. He doesn’t want to say how much he has spent – while hinting that we’re talking many millions of pounds – but even with bountiful reserves of cash, it was no easy task. The property’s condition when he bought it was “pretty shocking: there was 5ft of water in the basement and the top floor was derelict”.

“The first builder I employed advised me to sell it as fast as I could; the second said knock it down and build new,” he recalls. “But I bought it for the history and the heritage. Imagine the amount of work that went into building this. Yes, I spent a lot of money. Yes, I restored it. But the genius in the beginning was the people who designed it and built it. They were phenomenal.”

As he guides me round the 38,000 sq ft of immaculately restored and stupendously luxurious living space on four floors, you can see what he means: this house was well worth saving. From the cantilevered stone staircase, which winds in a graceful ellipse up three storeys, to the high windows, with the original thin, wavy glass between slender glazing bars, and the curved wooden doors opening into matching oval rooms at either end of the single-storey wings flanking the main house, the confident elegance of Georgian style and proportion, and the expert workmanship that created it, have been rightly rescued. And then some.

The entrance hall sets the tone: 24-carat gold leaf, liberally applied to the large pillars and restored crown mouldings in the ceiling, gleams in the high-watt dazzle of the huge chandelier. It is one of 47 throughout the house, all made by Wilkinson, in London.

The cleaning regime must be awesome: everything shines. The cream and gold upholstery on the ornate furniture around the two Portland-stone fireplaces is immaculate; the bust of Atlas on a marble pillar is blindingly white.

In the formal drawing room to the right – where the sun streams in through smear-free floor-to-ceiling windows – there is not a trace of dust in the folds of the heavy violet silk curtains.

Maybe the housekeeper, one of a permanent staff of 14, watches the maids at work on the network of security cameras. Made possible thanks to a comprehensive rewiring job, and indiscernible among the gilded coving, they allow almost total coverage of the house and grounds from various tele-vision screens around the property.

The sitting room to the left of the entrance hall strikes an informal note. “How do you like the elks? Imagine the speed they were going when they hit that wall,” Flatley deadpans. The great antlered heads peer out of a forest-green wall at either side of a marble fireplace. Moss-coloured leather sofas sit on one of the carpets Flatley commissioned for the house, this one with a pattern of pheasants woven into it. Piles of books on the coffee table enhance the comfy, clubby atmosphere.

“I don’t watch much TV; I love reading,” Flatley says, leading me to where the serious reading gets done. Opening a door off the ground-floor corridor that stretches “the length of a football pitch”, from the oval dining room at one end to the matching oval music room and bar at the other, he ushers me into the two-storey library.

When he bought Castlehyde, the space the library occupies “had white lino, old washing machines and a fluorescent light. I had a dream to build a two-level library, so I sacrificed the bedroom above and kept the windows for light”.

The upper reaches of the leather-bound books, including first editions of Shaw, Wilde, Yeats and Joyce – “Smell the paper on that,” he says reverently, handing me a copy of Ulysses – can be reached by a spiral staircase to the mezzanine. The ceiling is painted with views of the Castlehyde estate, and classical busts gaze sternly down.

Stephen Jeffery, owner of The Property Finders (Ireland), who has known the house for many years, reckons: “Flatley has restored the late-18th-century mansion into one of Europe’s finest houses, preserving it for the next century or more.”

The builders, engineers, artisans and gardeners employed in the transformation of Castlehyde were legion. The German owner from whom Flatley bought it had consolidated the neglect it had fallen into since the 1920s, when it was home to Douglas Hyde, who went on to become, in 1938, the first president of an independent Ireland.

“The house was raped,” Flatley says with some passion. “I had a call from a London auction house trying to sell me back the original dining-room table for a ridiculous sum of money. I don’t mind paying good money for something good, but I refuse to be taken advantage of.”

But, my, has he been on a shopping spree, evident in everything from the fabulous vintages in the two separate wine cellars – one for red and one for white – to the lavish decor of the six bedroom suites on the top floor. “All the bedrooms are themed, which I think is important,” says Flatley, who grew up in a two-bedroom house with his parents, brother and three sisters. Given the blitz-krieg of bright, shiny ostentation, from the gold monogrammed table napkins to the dozens of awards, show posters and lit-up cases of his old dancing shoes, the discovery of a Monet – a colourful seaside scene – tucked away in the dressing room of the master suite that occupies the whole first floor is a surprise.

Why hang it there? “Why not hang it there? It’s my room,” comes the spirited reply.

Flatley has other properties around the world: London; Villefranche-sur-Mer, in the south of France; Barbados; Chicago. He has just paid £700,000 for 56 acres on Rossmore Island, in Co Kerry, where he plans to build a house. But Castlehyde is home. “If it was good enough for the first president of Ireland,” he says, “then it’s good enough for me.”

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