But of all Reynolds’s portraits of period celebrities, the most titillating to his contemporaries were those that he did of the demi-monde: of the actresses and courtesans who moved among the social elite, exquisitely beautiful, coquettishly fey, feeding the exotic fantasies that flouted polite codes of behaviour.

Reynolds, who was “quite an operator”, according to Martin Postle, the curator, made a calculated decision to depict these women. Though they would have been firmly disapproved of in more conservative quarters (not least by Reynolds’s own sister, who feared that her sibling risked eternal damnation), they also attracted the invaluable publicity of gossip. Even as they scandalised, they fascinated too: and no wonder, when Kitty Fisher — she of the nursery rhyme — had a party trick of nibbling on banknotes slipped into sandwiches.

But Reynolds’s interest was more than a public relations exercise. He respected them as well. Like him they had hauled themselves up by their bootstraps. They were as much self-made women as he was a self-made man. And they pursued a vocation similar to his own. They were performers who, like artists, tested the parameters of convention, promoting the values of the liberated society that Reynolds also admired.

Perhaps this is why the 18th century is so often compared to our own. It had a freewheeling ease. It enjoyed conspicuous consumption. And yet, walking back home past Reynolds’s old studio in what was then the highly fashionable Leicester Square, I was accosted on the fringes of Soho by a woman who held out a petition. The prostitutes, who ever since Reynolds’s day have plied their trade in this famously bohemian area of London, find their livelihoods threatened by Westminster Council which — not unaware of soaring property prices — seeks the compulsory purchase of buildings identified as brothels.

These prostitutes have considerable support from local residents. Of course nobody wants to promote abuse and subjugation, but at the same time prostitution — the oldest profession, after gardening — is not going to vanish because its practitioners (who often work for themselves or as part of a collective) have been driven away. To evict them is simply to drive them out to the more perilous peripheries. Soho, apparently, is the safest area in Britain for the sex industry. So rather than ignoring the issue or turning primly away, we should confront it, and learn to respect the prostitute, as Reynolds did.

• ARTISTS HAVE always used sex to provoke and attract. Tracey Emin follows a time-tested marketing tactic when she titles her new show When I think about sex . . .

  In recounting her sad life story, a tale of rapes and abortions and bullying boyfriends, she has set out to challenge the mean-spirited and petty-minded. The ploy has certainly proved successful. But, like some 18th-century lady of the night, she has become as much vilified as admired and was recently elevated to a “100 Most Disliked” list. I can’t help feeling that to be on it she must be doing something right. But, in an interview last weekend, Emin suggested that she was ostracised because of her accent. “It’s the way I speak, innit,” she complained. Surely she’s not right? Reynolds, after all, had a strong Devon burr. And J. M. W. Turner — Margate’s second most famous painter — is said to have spoken with a Cockney accent all his life.

Though who knows how Father Shaun Middleton, who, I read, has been appointed as an in-house priest, would view it? He may prefer the strict line of John Musters of Colman Hall whose wife, another of Reynolds’s models, was coveted by a lascivious Prince of Wales. She ran so wild in London that her exasperated spouse had her painted her out of an equestrian portrait, substituting the figure of a sporting vicar instead.

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