Hey, big earner!

YOU'VE got to hand it to her. Dame Shirley Bassey may be 71, but second-best is clearly never going to be an option for a woman with more relationships behind her than Mata Hari.

"Some men are afraid to be with a successful woman, because we're so terribly strong. We know what we want and we're not weak and fragile," Bassey told an interviewer in no uncertain terms a few days ago.

"I've always been the breadwinner and many men don't like that, even in today's changed world. It's hard for a man to live with a successful woman. Very few men are generous enough to accept success in their women."

You can almost hear the swish of her feather boa. But Bassey is far from alone in her assertion. On Friday, Glasgow-born Clara Meadmore, a 105-year-old self-confessed virgin and retired secretary, revealed that being single was the key to her incredibly long life, saying: "I grew up in an era where little girls were to be seen and not heard, so I had to learn to stand up for myself and earn my own living. Some men don't like that in a woman."

The diamond diva's predicament is so common it even has its own, slightly dubious acronym: Swans – strong women achievers, no spouse. There are now more than five million single women across the UK, many of them successful, independently wealthy women who have no man in their life – either because they don't want one or because, as Bassey suggests, they are intimidating the poor poppets.

The theory that successful women intimidate men is not a new one. In 2002, the American writer Sylvia Ann Hewlett published a book, Creating A Life: Professional Women and the Quest for Children, which seemed to suggest that high-achieving women were unable to form lasting relationships.

She wrote: "Nowadays, the rule of thumb seems to be that the more successful the woman, the less likely it is she will find a husband or bear a child." She estimated that successful women who were still single at the age of 30 had less than a 10 per cent chance of ever marrying.

In 2004, researchers at the University of Michigan published a study that found men would prefer to marry a woman they considered to be their subordinate, rather than a superior or a peer. Later that year, the Scottish Mental Survey published data suggesting that women with higher IQ scores were less likely to marry than women with lower IQ scores, whereas the opposite was true for men.

But if it really is true that men are intimidated by successful women in these supposedly enlightened, equality-driven times, the question is: why?

"Often, what you'll find is that a woman has put all her energies into becoming successful in her career, not in a relationship," says relationship coach and Loose Women panelist Jenni Trent Hughes. "And those qualities that she's brought to her career are things like being very driven, focused, and very powerful. Men can find those qualities in a woman difficult to deal with. You can get into a situation where there's just too much testosterone in a relationship, and it's not going to work."

For some women, the knowledge that they are successful in their career makes them assume they will be unsuccessful in relationships. In her book Why Smart Men Marry Smart Women, Christine Whelan says: "Nearly half of single women believe their professional success is intimidating to the men they meet.

"Put another way, many high-achieving women think their success is not helping them find love. Some 66 per cent of Swans disagree with the statement 'My career or educational success increases my chances of getting married.'"

No wonder then, that some women feel they have to dumb down in order to attract a man, as Miranda famously did while speed-dating on an episode of Sex and the City – a successful lawyer, she pretended to be an air hostess.

Kate Harrison, author of novel The Starter Marriage, says: "I've met women who'll talk in a witty, intelligent way when they're around other women, but as soon as an eligible man turns up, appear to lose about 100 points off their IQ score and go rather doe-eyed and pouty. It does work with some men, but then you have to ask yourself if those are the kind of men you want to attract."

But surely smart, successful Swans shouldn't have to resort to such airhead tactics in order to snag a mate? Candace Bushnell, author of Sex and the City and the undisputed queen of single women everywhere (until she married at the age of 40) remarked recently that the playing field had fundamentally changed.

"What we all need to understand is that career women are here to stay, and they're renegotiating the rules of relationships and marriage and motherhood," she said.

With more girls in Britain now gaining first-class degrees than boys and the country's top corporate institutions filling with bright, successful young women, it's about time men started to accept that the Swans are here to stay – and that the "NS" (No Spouse) is negotiable.

Interestingly, Whelan counters that the statistics around successful women are flawed, in that they examine only very specific age groups.

In fact, some research suggests that increasing success makes marriage more likely, not less. A study at the University of California, Los Angeles, found that among white women, a $10,000-per-year increase in salary (about 5,700) can mean a 7 per cent increase in the likelihood that she will marry within a year.

"High-achieving women marry at the same rate as all other women; they just do so a bit later in life," writes Whelan. "Smart women do get married. Men do make passes at girls who wear glasses. And though some men are looking for women to play fetch for them, there's no shortage of men who would much prefer to volley with an equal."

Let's hope one of them gives Dame Shirley a call soon.

THE MEN IN SHIRLEY BASSEY'S LIFE

• KENNETH HUME

Bassey married the TV director Kenneth Hume in 1961, an act that shocked the showbiz world, most of whom were aware that Hume was openly gay. She defended the relationship, saying he made her laugh. However, they married and divorced twice within a three-year period (during which she had an affair with the actor Peter Finch, who is thought to be the father of her daughter, Samantha). He committed suicide in 1967, leaving Bassey devastated. "I was so angry with Kenneth for leaving me like that," she said once. "How could he do this to me? And why?"

• PEPE DAVIS

One of Bassey's first serious boyfriends, Davis seems to have been an early candidate for the sort of man who struggled to accept her success. Around the time she had her first No 1 hit, As I Love You, in 1958, police were called to her hotel room when he threatened to shoot her in a fit of jealousy, holding a loaded gun to her stomach. They split up soon after.

• SERGIO NOVAK

Bassey married Sergio Novak, in 1968 in Las Vegas. An Italian music producer, Novak became her manager and they spent several years living in tax exile in Switzerland. They adopted a son, Mark, but divorced after nine years. Bassey later reflected: "You can't take a contract to bed with you."

• GREG SMITH

Bassey's last serious boyfriend. In 2003 she had a whirlwind affair with Smith, a dashing theatre producer who had been married to both Michael Barrymore's (now deceased) ex-wife and manager, Cheryl, and the actress Lynda Bellingham. In an interview during their relationship, she said: "I can't help feeling that if I get too happy it will be taken from me." They split up a few months later.

• JAMES BOND

Perhaps the most constant presence in Bassey's life, the spy who loved her has been responsible for three of the diva's biggest hits, including, of course, the show-stopper Goldfinger. Even now, in her stage shows, she always performs a James Bond medley. Diamonds may indeed be for ever, but the only man in Bassey's life these days is a fictional one.