The National Lottery is this month celebrating its 15th anniversary, with licensee Camelot ­staging parties for past winners all round the UK, including a gathering at Hampden Park for some of Scotland’s 436 big winners, among them 190 millionaires or multi-millionaires since 1994.

Lotto winner John McGuinness, however, was a notable absentee from the Scottish prizewinners’ bash.

McGuinness, 45, one of the earliest and biggest winners in the UK when in January 1996 he picked up £10,055,900, said last month he was broke.

Lottery winners are not the only people who come into sudden wealth. Ordinary folk with an unexpected pay-out from inheritance, insurance, or divorce, along with budding sports or entertainment stars, and business owners or entrepreneurs who are made an offer they can’t refuse, can all find themselves rich overnight. But what are the dangers awaiting those who may have too much money, rather than too little?

Even the savviest entrepreneurs are prey to seeing millions disappear. Transport tycoons Brian Souter and Ann Gloag claim they are owed £18 million by City financier Nick Levene, who last weekend emerged from hiding to say he was seeking treatment for gambling addiction and was co-operating with Serious Fraud Office inquiries. Levene promised his clients big profits from his “special access” to investment opportunities, and the pitch landed £10m from Souter and Gloag.

Lord Jacobs of Belgravia is one of Britain’s richest men, with a personal fortune of more than £100m, a long and distinguished career in business, and a reputation as a philanthropist.

Yet he has admitted to being among the roll-call of glitterati who handed over millions of dollars to the convicted New York fraudster Bernard Madoff.

Scottish-based financial planner Duncan Glassey has built a business on advising the suddenly wealthy, and steering them away from becoming almost as suddenly poor again. “We are all capable of making the wrong investment decisions based on greed and naivete,” Glassey says.

“One lady came to me having lost her lottery win on a fraudulent investment scheme. She had invested £750,000 won by her fiancé, on the promise of a 50% return on her investment. The lady was knowledgeable on financial matters and had a successful private practice as a psychologist. But what she knew didn’t influence her behaviour.”

He goes on: “People who receive sudden wealth often suffer great frustration over how to deal with such a large amount of money. For some this results in a painful inability to identify real needs and longings, or to connect with meaningful work or occupation. Others find it difficult to establish authentic and trusting friendships.”

An international survey found that 35% of lottery winners turn out to be bankrupt within 10 years.

“In drawing up a plan we often find that if they buy the lovely house that they have always dreamed about, get the cars they want, give the gifts they want to brothers, sisters and close family, then the money will run out after about five years,” Glassey says. “The first mistake people make if they win £1m or £2m is they think they can live a millionaire’s lifestyle.”

Only a month ago, nine regulars at the Doon Inn in Blantyre scooped a £4,525,058 win from their lottery syndicate, triggering windfalls of over £500,000 for each of them. But is that enough to retire?

An Aberdeen-based deep-sea diver on six-figure earnings consulted Glassey after a big lottery win. “He said, ‘unless I can go to Portugal every weekend and play golf and not have to work, I am going back to work on Monday’. He was aware he couldn’t otherwise maintain his current lifestyle – it’s unusual for someone to be so level-headed.”

Since their £2.9m syndicate win in February 2007, the staff of Smile hair and beauty in Burnside, Lanarkshire, have all paid off their mortgages and bought new homes and cars. But though two have retired, Wendy Brown, Natalie McGuire, Lorna Alexander and Megan McCann all still work together at the salon.

But most dramatic was the winner who Glassey encountered while advising in Edinburgh on behalf of Ernst & Young in the lottery’s early days.

“He owed his best friend £500 and couldn’t pay him back, so he tried the lottery. He won £1.5m, paid his friend back, and came to see E&Y. He said he was going to give all the money to the Salvation Army, and had made the decision not to tell his wife or his children. He was an Irishman with a big family of seven, they were incredibly close and he was terrified this money was going to influence them.”

Glassey recalls: “In many ways I really respected the guy. But the downside was that he never took any advice. Today, I would probably try a lot harder to persuade him to put money in trust for children or grandchildren’s education, to take a long-term view.”

McGuinness was a hospital porter who blew most of his £10m win on sports cars, luxury holidays, a mansion in Lanarkshire, and ploughing cash into Livingston Football Club, though he gave £3m away to family and friends.

“I thought I’d plenty of money and what was a few million to invest in a football club,” he said in a recent interview. “Now I’m worried about how to pay for the shopping.”

Glassey observes: “For many people whose experiences were not positive, much of the damage has its roots in non-financial matters. Many simply did not know how to handle the attention and emotions involved, and they were not prepared to make the decisions and set the boundaries that were necessary …

“Many people have stories of scams, bankruptcies, and unexpected losses. Lottery winners have told me about spending binges and how they hid money from their spouses. There is often an unbalanced relationship with money which can manifest itself as shame, guilt, anger, fear, rampant materialism, hoarding and all manner of addictive or compulsive behaviour.”

Camelot has a panel of 10 financial advisory firms and 10 legal firms standing by every week for all winners of prizes over £50,000. “The IFAs are all assessed on their independence, their charging structure and their expertise and knowledge,” says Camelot’s Rob Dwight.

That definition would appear to rule out going to the bank for advice. “We see winners before everyone else, in the privacy of their own home – though understandably you may get winners who shout it from the rooftops, and a bank or building society may see an opportunity to push their services forward.”

Glassey recalls: “We came across horror stories where the winner said the bank had contacted them, and they had put all the money into a with-profits bond. Luckily, on some occasions it was within a 14-day cooling-off period – but on some occasions we arrived too late.”

He adds: “In those days Royal Bank of Scotland was known to send round a limousine to pick up a (lottery-winning) client for a meeting with the bank manager – for some people that is a wow factor.”

So what is best advice for a newly minted millionaire?

“It goes from the very practical, to changing the telephone number and organising a PO box number, in case people are trying to contact them remotely or track them down, to giving them the first advice – do nothing for 12 months, yes, you have hit the jackpot but what do you want to do with it?”

Next comes a gradual initiation into financial jargon, the meaning of risk, and building a life plan. Investment would be “low-risk in the first couple of years until they become more knowledgeable”. A typical spread at the outset would be 70% in gilts, high-quality corporate bonds and cash spread among different institutions in £50,000 chunks, and 30% in equity funds with very widely diversified holdings.

Advisers should charge on the basis of ongoing service, not products.

Glassey concludes: “Money is the single most transformational substance in our society. It is seductive, alluring, fascinating, and perceived as greatly desirable. It is everyone’s dream – but you must be mentally prepared.”