One of Britain's youngest lottery millionaires has been found dead at 29.

Stuart Donnelly was discovered at the luxury home he bought after winning almost £2 million (US$2.98 million) when he was 17.

When he hit the jackpot in 1997, sharing the £25 million prize fund with 12 other winners, he toasted with Coca-Cola because he was too young for champagne.

But his instant riches made him unhappy and he appeared increasingly unable to handle the strain of being a millionaire, friends said.

He moved away from his home town, where most of his friends lived, and then, just two years after his win, his beloved father — described as his 'best friend' — died.

In recent years, Mr Donnelly admitted on the social networking site Bebo that he hated socialising and had become a recluse, listing his activities as: 'Sleeping, watching TV, listening to music, surfing the net. Basically, anything that involves not leaving the house.'

On Thursday, police in Scotland said his body had been found at his remote cottage in Castle Douglas, Kirkcudbrightshire, on Wednesday morning.

They have launched an investigation but said there were no suspicious circumstances.

Sources added Mr Donnelly was believed to have suffered from health problems, and that at this stage his death was being attributed to natural causes.

Family members including his maternal grandmother have cut short their New Year holiday in Portugal to fly home, after being informed of the tragedy.

When he struck gold in 1997, Mr Donnelly was a college student living on a council estate and earning £60 a week working part-time in a small chemist shop.

He quickly abandoned his pharmaceutical course, took his friends on a holiday to Thailand and bought a £2,000 executive seat at Celtic Park to watch his beloved football team's home games.

He splashed out £90,000 to buy his divorced mother May a house, and purchased the secluded villa for himself, where he cared for his father Daniel who was a polio sufferer.

He also gave £15,000 to Yorkhill Hospital in Glasgow, where his younger brother Shaun was treated for a genetic disorder.

But in a 2003 interview, he told how he was struggling with winning at such a young age.

He said: 'It was very hard to deal with all the attention I got. I even had people camping outside my house. It put a huge strain on me and my family.'

On his Bebo page, messages dating back several years show the kind of attention he was receiving, with 'old friends' posting comments such as: 'Hey Stuart, remember me?', and 'You still got your winnings?'.

On Thursday, mourners left more messages, with one writing: 'You make me sick, you only befriended this poor lad when he won the lotto.

'Most of you are the reason this poor lad died.'

When he won, his father proudly proclaimed: 'I couldn't get a better son. He's the nicest person you could meet. Stuart doesn't drink, smoke or take drugs.

'He's here to look after me round the clock. I'm not just saying that because he's worth a few bob. Even if he wasn't a millionaire, he would still be a super son.'

Daniel Donnelly's death — of a heart attack aged 45 when on holiday in Thailand — left his son devastated.

Their luxury cottage, which can be reached only by a single track, became his retreat, and Mr Donnelly cut himself off from the world, with even his mother complaining at the time: 'I phone him, but most times I get his answer phone.'

Locals back in his home town of Neilston, East Renfrewshire, just south of Glasgow, rarely saw Mr Donnelly since he moved away.

Last night, his aunt Elaine Calderwood, posted a message on his Bebo page which read: 'Stuart is very close to his family and spent Christmas with his family and travelled home to his own house after the festive season.

'The post mortem will confirm the medical condition that caused his death. The doctors had been testing Stuart and had not diagnosed his illness.'

She added: 'Stuart was loved by all his family.'

Thanks to rdgrnr for the tip.