When Englishman Chris Gregory went for a brain operation, he knew it would be a life altering event.

But he could never have imagined that it would be a nationality-altering: when Gregory woke up, he stunned doctors, nurses and his wife when he started speaking with a strong Dublin accent, and singing “Danny Boy.”

Gregory, who had the operation after rupturing a blood vessel in his brain, had an extremely rare condition known as “Foreign Accent Syndrome.”

The condition can be triggered by a stroke or head injury, when the tiny parts of the brain that control speech and language are damaged.

The man, who has spent all his life in Sheffield, Yorkshire, has no family ties with Ireland, and has never even visited the country, woke up after having been on a life support machine for three days.

After waking up, the 30-year-old landscape gardener told his wife, Mary:"You're the fabbest girl I know,” and said “It's da broid” (Dublin-ese for “it’s the bride) in a strong Dublin accent.

And half an hour later, he was back to his old Yorkshire self.

His wife, Mary, told a British paper: “'I couldn’t believe it when I walked on to the ward and heard someone singing Danny Boy really loud. It sounded like a drunken Irishman, and all the racket seemed to coming from the direction of Chris’s bed.

“I thought to myself: 'It can’t possibly be him…' But when I pulled back the curtains Chris was sitting up in bed belting out the tune with all the right words and the thick Irish accent like he’d grown up in Dublin and lived there all his life.

“All the nurses were trying really hard not to laugh, and I was too. I just couldn’t take it in at first, it seemed so comical, but it didn’t matter at all because I’d been so worried about losing him altogether.

“Chris’s Yorkshire accent had vanished completely, and he was talking like an Irishman all the time.

Chris said."I just don't a remember a thing about it -- I wish I'd been able to listen to it all, but I don't have any recollection of what happened when I came round,”

"I've never had any connection with Ireland or the Irish people, that's what makes it so odd, but I'm looking forward to going over there for the first time."

The syndrome was first noticed in the 1940s, when a Norwegian woman who was hit by shrapnel in the head following a German bombing raid developed a German accent.

The unfortunate woman was branded a spy, and shunned by her friends and neighbors. Since then, there have been around 50 cases recorded of the syndrome.