SHE HAD so many. But she wanted more. For over a century, Mills & Boon readers have fallen in love with “The Mediterranean Tycoon”; delighted with “The virgin wife of the Italian millionaire”; vanishes before “The Secret Passion of the Greek” (which comes after “The Mistress of the Greek Magnate” and, somewhat inevitably, before “The Secret Child of the Greek Magnate”). Yet, they whispered, something was missing. Effective contraception, perhaps. But also diversity.

Lately, his absence has seen the world of romantic fiction smolder even more than usual. The heroes are all tall and beautiful, but they rarely are, critics point out, so gloomy. “The romance is still too white,” says Nadine Gonzalez, a Haitian-American author now published by Mills & Boon. The publisher launched a competition to find writers from “underrepresented ethnicities” in order to “bring more diverse characters” to the genre.

Mills & Boon has long been an indicator of British society, across the board, from sexual attitudes (business was once consumed by a kiss; now the word ‘wet’ is used regularly) to climate change (an increasing number of heroes work in conservation). Feminism arrived at the end of the last century, when the publisher informed aspiring writers that the heroine “doesn’t have to be a career girl” but could have a job, even “a little bit. female ”, as a doctor.

The headlines say a lot about expanding the horizons of the British. One in 1956 was called “Romance Goes Tenting”; those today include “Reclaimed by the Mighty Sheikh”, “The Argentinian’s Request” and “Penniless Virgin to the Sicilian Bride”. Italian heroes work well, says Sharon Kendrick, the author of over a hundred titles (they are seen as sybarites). The Greeks (enigmatic) and the sheikhs (masters) too, but not the French (infidels) or the English (classified).

In her novels for other romance editors, Ms. Gonzalez has written about African-American, African-Cuban, and half-British, half-Jamaican heroes. The hero changes in other ways as well, she said. In the old days he had to be emotionally repressed; now, if he is to be confident, he “doesn’t need to brood.”

But some kinds of diversity seem more distant than ever. Ms. Gonzalez says she has never seen a hero smaller than the heroine, and that a bald head would be “one step too far”. So, it seems, a man of modest means would do. A current series is called “Marrying a Tycoon”; there isn’t one called “Marry an Electrician”, or “Marry a Journalist”. Here, only inflation brings the change. Heroes were once millionaires, says Ms. Kendrick. “They are all billionaires now.”

This article appeared in the Great Britain section of the print edition under the headline “Big, Beautiful and Darker”