Jeer if you will, but I was shocked by the latest Bridget Jones book, Mad About the Boy. I was shocked by the sex. No, honestly. Compared with its predecessors, including a one-off series about how Bridget got pregnant but wasn’t sure by whom, this latest book ratchets up the raunch quite markedly.

Granted, Bridget is having it off with a boy of 29 (to her 51), but there weren’t any passages from her previous diaries like this: ‘Oh God. What was I thinking having sex all night? The whole makeup/breakup thing somehow whipped Roxster and me up into a sexual frenzy and neither of us could stay asleep. Was actually hanging upside down from the side of the bed with Roxster holding both my legs in the air whilst thrusting in between them when suddenly —’. That’s not the half of it. There’s a bit about the tribulations of her friend Jude who is meeting men from dating websites and has ended up with a bloke who is into sexual humiliation. Gross.

Now, you can find far more graphic stuff than this via any search engine. But what’s unsettling about Bridget’s new candour is that this is mainstream stuff. We all know about society being sexualised and dimly grasp it’s to do with online pornography but it’s only when sort-of respectable, everyday, institutional, middle-class elements start talking dirty and dressing like tarts that you realise that the rot really has set in and that, as cancer doctors say about the spread of a tumour to the extent it’s inoperable, it’s in the grass.

There are other things that bring home to you that our sensibilities have coarsened, that what once seemed like perversity has been normalised. I’m still trying to get my head around Channel 4’s Sex Box, in which people — disabled, ethnic minority, gay — go into an, er, box in a TV studio, have sex in the presence of an audience, and then come out to talk about it with Mariella Frostrup.

Princess Eugenie twerking with a bear — this being a term I’d never even come across before I saw pictures in the Daily Mail of the Queen’s granddaughter simulating sex with a stuffed animal — was shocking on a couple of counts. One that she was doing the sort of thing normally seen on YouTube in connection with Miley Cyrus; the other that it was being reported in the Mail, and, come to that, the Telegraph. That’s the thing about graphic stuff getting into the water… it happens, then it is circulated among people who graze on the internet; then it gets reported and condemned in the middle-class press, which has the curious effect of normalising the thing.

Former Disney star Miley Cyrus Photo: Getty

So what starts out with the singer Rihanna doing preposterous things around a pole, or former Disney star Miley Cyrus gyrating on a wrecking ball, ends up being recycled and familiarised through controversy, though given that Rihanna’s latest video has been viewed 23 million times since last Wednesday, she probably didn’t need any help. I was only made aware of these videos after they were condemned by Annie Lennox, who observed: ‘It seems obvious that certain record companies are peddling highly stylised pornography with musical accompaniment… It’s a glorified and monetised form of self-harm.’

Rihanna’s latest video for ‘Pour it up’ was banned only 10 minutes after its debut Photo: Getty

My instinct at this point is to retreat under the duvet, but you can’t isolate yourself from the new and pervy aspects of the culture because they get to you one way or another. I’ve never read Fifty Shades of Grey, for instance: 70 million readers can be wrong. But I can’t not buy knickers in M&S. Yet even there, bondage/dominatrix themes, apparently inspired by Fifty Shades, are coming to the lingerie section. The latest Autograph collection is risqué, in that the silhouette shades into SM, and the multiple ribbon straps and cutout designs are suggestive of bondage.

The way in which high-end lingerie boutiques have brought the darker side of Soho on to bourgeois wishlists deserves an essay of its own. Once, to get nipple clamps and spanking paddles you had to venture into dodgy shops; now you go to Covent Garden. I realise that sex shops are nothing new and in other parts of Europe they’re more in-your-face; what’s different is that this is middle-class aspirational shopping, boudoir-boutique stuff that features in newspaper women’s pages. Soho has, spiritually, invaded the high street.

What the effect of the sexualisation of the culture will be is anyone’s guess. We know already that explicit social media content has affected the confidence of girls and the expectations of boys. But it goes further than that, doesn’t it? The normalisation of what was once pervy may end up creating sexual insecurity, whereby people feel inadequate if they don’t engage in the kind of sex they read about, or are intimidated by what they assume are everyone else’s expectations, or feel aggrieved because they’re excluded from what they imagine everyone else is at. I’m not sure the change in culture has made Brits enjoy sex more.