What makes a generation of women fall in love with Byron, or David Cassidy, or Rudolph Valentino, or Elvis? Why do women of one era find something attractive that would revolt their great-grandchildren, or great-grandmothers?
Eugen Sandow, the burly Victorian strongman, was thought to have the perfect male body. Women were said to have thrown jewellery on to the stage as he performed, and queued up to fondle his muscles.
But by the 1920s, the ideal male torso had become far less bulgy, and slim-hipped Rudolph Valentino types with slicked-back hair were more in demand.
As cinema was taking off, the parallel boom in radio meant that women could be crooned to by the stars - alone in their own homes. Rudy Vallée was labelled "the vocal Valentino" and, less romantically, "the guy with the cock in his voice". A shortage of men after World War1 meant many women in the '20s and '30s could only dream of being wooed in this way.
In the '50s, married women confined to domesticity often had a hard time of it; this was the decade of Betty Friedan's The Feminine Mystique, housewives' psychosis, and the rising consumption of tranquillisers such as Valium.
With women placing faith in the family doctor, medical romances became popular - in 1957, a quarter of Mills & Boon novels concerned doctors - and made a star out of Dirk Bogarde in 1954's Doctor in the House.All this enthusiasm for Prince Charming in the '50s fed into the popularity of one of the oddest celebrities of the decade, the showman pianist Wladziu Valentino Liberace, who tended to dress on stage like a pantomime prince.
He and the huge star of the era, Elvis, were trying out a new, more opulent style of masculinity, and female fans appeared to revel in it. Although he had to endure homophobic heckling from men, Liberace claimed to receive 6,000 to 10,000 letters a week from female fans, and many proposals of marriage.The rise of the women's movement coincided with a boom in the sale of the sort of popular romance novel that feminists were increasingly vocal in deploring.
In a notorious and much-regretted 1970 interview, the Mills & Boon novelist Violet Winspear said her "hard-muscled" heroes had to be "the sort of men who are capable of rape: men it's dangerous to be alone in the room with".
Feminists also worried about the popularity among young girls of the magazine Jackie, which promoted the message that selfless, feminine behaviour would eventually earn a boy's true love, and reached a UK circulation of 606,000 in 1976. The most popular of Jackie's pin-ups was David Cassidy, a singer sneered at by men for his Bambi-like looks but seen by girls as one of their own...