More than her cancelled gigs, that blood-spattered street scrap with her boyfriend, more even than her recent overdose, nothing bespeaks the inner mess of poor, brilliant Amy Winehouse than what is written on her body. At the Mercury awards this week she resembled a Barbie doll attacked by an additive-high, felt-tip wielding toddler: tattooed on her arms are crude, topless “pin-ups”, the sort once beloved of sailors and truckers, and then, incongruously, “Cynthia”, the name, apparently, of Winehouse’s late grandmother.

Her dear old gran must be turning in her urn to know that she’s been commemorated thus, I remarked to my hairdresser. But she gestured to a cherubic 19-year-old junior bent over the backwash, the word “Nan” visible on her upper arm. A friend says the worst tattoo he ever saw was on a young woman who, in thick, black type circling the nape of her neck, had the legend “I love you Granny and Grandad Wilkinson”.

On one level this desire to remember a loved, elderly relative is rather sweet and touching. Yet why not write a poem, frame a photo, place flowers on a grave? Why inscribe your body so permanently, so painfully? But we live in an age where the young believe their private feelings can be validated only when exhibited in a public domain. It is no coincidence that tattooing has grown over the past decade in parallel to the internet with its myriad opportunities for personal expression: the body as home page.

Once the mark of the criminal, rock star or squaddie, now one in five British people has a tattoo. Indeed, rare is the young woman I come across at the gym who lacks a butterfly on her shoulder blades, or some gnomic squiggle peeping over her hipsters. Tattooing is usually dismissed as fashion. And surely only a dim-bulb or lowlife would subscribe to something so permanent for such an ephemeral purpose? But while tattoo trends change – Celtic crosses are so mid-90s, Chinese characters totally last year, it’s all funky, elongated stars now – tattooing has endured, becoming ever more déclassé, until Samantha Cameron, a baronet’s daughter and Tory first lady, embellishes her ankle with a dolphin.

So why is this urge growing? While not everyone is sheepishly following David Beckham, his adventures in ink are illuminating. I recall a documentary early in his fame, when with Victoria spicing it up in America, Becks was alone in his Cheshire pad, pondering how best to mark his adoration. (Posh had already had the date of their first shag printed on to her foot.) In utter seriousness Beckham explained that he wanted his beloved’s name in a foreign script and, to see how it would look, had copied on to his arm in Biro some Chinese characters from a takeaway menu.

A surfeit of emotion with no satisfying medium – no poetry or liturgy – to express it, no way to pin down the moment, to express the spiritual or eternal: Beckham echoes his generation. An unprecedented confidence and pride in the physical self is combined with an absence of religious ritual. And so the body becomes literally a temple. The message is deliberately mystified: awkward or commonplace sentiments sound deeper, less banal in a foreign script. Latin is classy, magical. Angelina Jolie has “ Quod me nutrit me destruit” (What nourishes me also destroys me) besides, in English, “Know your rights”, like a walking billboard for the Citizens Advice Bureau. French is exotic enough for Robbie Williams, who is inscribed with “ Chacun à son goût” (Each to his own). Beckham eventually opted for Victoria in (misspelt) Hindi.

And there is egotism, too, that others would wish to be confronted, on first meeting, by your deepest feelings, your checklist of loved ones. This spring in Australia, I was amused to read about a fight between two Aussie Rules footballers. A player called Adam Sellwood, seeing what he assumed was a tattoo of a girlfriend on the forearm of his opponent, Des Headland, remarked, charmingly: “I f***ed her last night.” Yet the tattoo, it transpired, was of Headland’s six-year-old daughter Madison.

In Sellwood’s defence, Australia is the world capital of rubbish tattoos. But why try to capture something as fast-evolving as a young child’s face? Tattoos express an arrogance about time, that the present moment is all that matters, an inability to imagine that an arse rose etched at 25 won’t expand into a cauliflower by middle age.

Celebrities, who do not worry or care that a ragbag of clashing Cape Fear-esq daubings might scare away potential employers, are free to deface their bodies with every “deep” homily they come across on the internet or passing lover. But increasingly a tattoo is widely seen as an appropriate way to mark some spurious moment of “personal growth”: a baby, climbing Machu Picchu, a divorce – even though after 30 a tattoo, like wearing a slogan badge or an angry T-shirt, seems a juvenile means of self-expression. But if we are powerless to change our lives, at least we can change our bodies, mark a new chapter with a blurry rose or a quote from the Chemical Brothers.

And the growth of middle-class tattoos reveals how we all yearn to be rebels now. Among today’s sixtysomethings only Marianne Faithfull and Helen Mirren bear the needle marks of a rock’n’roll youth. George Orwell, it was revealed in recent documents, had his knuckles tattooed with blue grapefruit-like shapes, to signify to his fellow colonial civil servants in Burma – and to reassure himself – that he was no imperial lackey.

But in the age of the global brand we must all be a bit confrontational and hard-sell. A tattoo becomes the mark of our difference, our personal logo. Even though a Maori armband tattoo is about as individual as a barcode on a packet of biscuits. In her book Bodies of Inscription: A Cultural History of the Modern Tattoo Community Margo DeMello remarks that while the middle class regard working-class tattoos as formulaic and ugly, they regard their own as “art”: exclusive, unique and of intrinsic merit. How hard the TV presenter Fern Cotton must have struggled to choose a fern to adorn her hip. And did Sam Cameron pore over the book of designs, reject a tiger (too aggressive), a flower (not edgy enough), before alighting on the dolphin.

“Yes, that’s me – even as I sip tea with the Tory matrons of Reigate, not quite rockin’ Amy Housewine, but nonetheless, wild, playful and free.”

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