The entertainer locked herself in a "panic room" and activated a panic button after discovering that a man had made his way through the castle's defences. The intruder, who tied up a maid during the two-hour incident, made his escape before police arrived.
Enya, 44, who has sold tens of millions of albums of her songs worldwide, never goes on concert tours and makes only rare public appearances. She lives a quiet life in the opulent village of Killiney, just south of Dublin, working on her intricately crafted CDs with a husband-and-wife team who provide lyrics and recording expertise.
In the incident, which happened some weeks ago, the intruder opened a safe but stole only personal items, leaving cash and valuables. A week earlier there had been another break-in, after which Irish police arrested a man, said to be English.
The singer has suffered before from the attentions of unwanted fans: in 1996 an Italian man, who had been seen in Dublin wearing her photograph around his neck, stabbed himself after being ejected from her parents' pub in Donegal.
Ireland is home to an unusually large number of famous artists, some home-grown like Enya, members of the band U2 and Van Morrison, while others have moved there from abroad. Some are attracted by a tax exemption which can save them millions.
Enya has lived in her small castle at Killiney for some years. She has made extensive changes to the premises, increasing its security precautions with alterations to its perimeter. She has applied for permission to make its walls even higher. Although the home is described as a fortress, its defences evidently continue to have vulnerable spots.
A business expert coined the phrase "enyanomics", praising her ability to sell millions of albums without giving live performances. He forecast a pattern "that allows individuals to amass large global fortunes for themselves and their companies from the comfort of their home base".
Enya, whose real name is Eithne Brennan, has opted for a particularly quiet life, choosing to remain unmarried and without children. This is in contrast to an upbringing which she has described as "continual hustle and bustle and crying and chaos". She once said: "The music I like best is silence." She had four brothers and four sisters, and her mother and father were involved in the music business as part of a travelling band, playing traditional Irish music.
In her solo career Enya has moved from the earthy to the ethereal, developing a distinctive style combining the mystical, the classical and folk influences, sometimes singing in Gaelic or Latin.
Her already successful career received a huge boost when her song "Only Time" came to be associated with the passions generated by the September 11 terror attacks in the United States.
Her sisters have also sold millions of albums as the group Clannad, of which she was once a member.
Her father, Leo Brennan, is a musical institution in Donegal, with an open and gregarious lifestyle in contrast with that of his daughter.
His pub, Leo's Tavern, and attracts many visitors who can inspect the family's silver, gold and platinum discs on its walls. Leo often takes to its small stage to sing Irish songs for the coachloads of tourists who call there.
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