Christa D'Souza

Most little girls want to be older than they actually are, but me, I'd say, maybe more than most. Fortunately, or perhaps unfortunately, my mother, only just 17 when she had me, never had the energy to keep that in check. I was hideously precocious in my tweens – Sacha studded platforms, full make-up by the age of 10. The upshot was that when my mother finally managed to pack me off, kicking and screaming, to boarding school, I was way more "advanced" than my peers, who to begin with ostracised me for it mercilessly. Looking back, of course, the other girls – a pretty homogeneous lot – were probably quite envious. Meanwhile, nobody's mother was as pretty or young as mine, and I always longed for sports day, when I could show her off.

Boarding school was one long, dull round of bending the rules, turning up the waistband of one's regulation grey skirt to make it that bit shorter, using talc as face powder and Vaseline as "lipstick", boasting about using Tampax, even though most of us were still using sanitary towels, and managing not to get precious bits of mufti, bought during the school holidays from Biba and Bus Stop, confiscated. The gulf between life at school and life at home, where there were no boundaries or rules, was so huge it sometimes took my breath away.

Looking old for your age can be a boon, but it can also be wrong-footing. I remember, at the age of about 12, being quite seriously propositioned by a friend of a friend of my mother's at one of the numerous dos she gave at our house. I never told her. Typically, I thought it must have been my fault.

Back home, we hung out a lot, my mother, my younger sister and me (my parents separated when I was about four). Because I always looked much, much older than my age (I was sold a ticket to A Clockwork Orange at the age of 11) and because my mum not only looked young for her age but was young, we were always getting mistaken for sisters.

Unlike my younger sister, who got to go to a co-ed boarding school, I was quite late on the boyfriend front. Not through lack of trying; it's just that I didn't actually meet any boys of my own age. And those I eventually did meet, more often than not, used me as a conduit to get to my mum. Like the older brother of a friend who, after carelessly tossing me aside, later pitched up at her laboratory at the Wellcome Institute and made a pass at her. She brushed him off like a fly, of course, silly little 17-year-old that he was, but it was a blow because it happened while I was pining away at boarding school.

As you can imagine, the floodgates opened when I hit university in America. What was the point, after all, of getting fitted with a diaphragm if not to use it? And besides, insecure person that I was, it was the least I could do in return for being actually fancied. Oh God. That diaphragm. I remember one impaling moment when I upended my bag by mistake while walking between classes and watched, along with everyone else, as it rolled out across the college quad. Those really were the days, sleeping around, downing vast quantities of drugs, obsessing about getting backstage at rock concerts, dressing up for rock concerts, eating badly, having my heart broken, sleeping around. I don't miss them one tiny little bit.

I didn't, that is, until I hit 50. Not the sleeping around bit, obviously, but the other stuff. See, if you are in a profoundly long-term relationship, as I am, and you are past the stage of sleepless nights with your kids, you start hankering for those bad old days – well, the good bits, anyway. Is this a final fling before the incontinence pants and slippers? Who knows, but where once I wanted to fast-forward, now I feel the urge to rewind.

Oh yes, in the youth of old age I can cane it just the way I did when I was 18, perhaps, dare I say it, even more with the security of a loving partner and my own roof over my head. (And oh goodness, some of the mates my stepsons bring home from university. Is it me, or is male youth about a million times cuter than it was in the mid-70s?)

So, yes, of course I'll be going to Glasto. But not so much to listen to the music (since my tastes stop somewhere circa 1976) as to experience the inappropriate thrill of being trashed. Because I am an old person, though, I cannot do it every night, so what I will do, as I did last year, is go in on the Friday and then spend the rest of the weekend with my middle-aged girlfriends at our cottage nearby with proper loos, a Nespresso machine and decent farm-shop food, painting our nails inappropriate shades of lilac, sunbathing in our sports bras, exercising our "mum and dad dancing" skills to nice, safe music such as Fleet Foxes and Elbow.

Talking of which, you should have seen me and a fellow fiftysomething the other night, throwing a few shapes to Supertramp after drinking too much rosé at dinner. Thank goodness my children weren't around, my children who so despair of the way their 50-year-old mother can dress of an evening, my children who still joke to their friends about how I used to call Florence + The Machine Florence + The Mission. (Patterns repeat I guess. My mum used to call Sade "Chardonnay".)

Not pretty, in other words, but the marvellous thing about acting inappropriately for one's age is that it really does make you feel like an 18-year-old again. Yes, one might feel like a 75-year-old the morning after, but it is a price that, for the moment, I'm willing to pay. Look away if you must.

Lucy Mangan: 'I couldn’t wait to become an adult, just so that I could be friends with these interesting people who read books, had all kinds of jobs, went to plays and stuff, and didn’t spend hours dicking about.' Photograph: David Yeo for the Guardian

Lucy Mangan

"You were born 35!" This is what Jenni, the lady next door who used to look after me if Mum was working late, used to say to me – sometimes with a smile, sometimes with a slightly weary, baffled look, sometimes with simple resignation.

I thought she was right then – which probably only goes to prove the correctness of her instinct – and I think she was right now. I was very, very bad at being a child. I was worse at being a teenager. Now, I am busy trying to fake my way through life as a normal 36-year-old, even though by Jenni's logic and my own internal clock, I am now 71.

Being old for your age has some immense practical advantages. The greatest benefit the genetic lottery can bestow upon anyone (after big boobs or great hair, of course) is a maturity that outpaces your chronological age. It allows you to vault over many obstacles that handicap other, more normal children. (I should explicitly state here, although I hope it will become clear, that I mean nothing pejorative by that. Normal is good. Children like I was are only in receipt of a random and flawed gift that renders them at least as weird and unsettling to themselves and others as it does untroublesome to teachers and parents. But we'll come back to that.)

At one level, it simply enables you to sit quietly for longer, pay closer attention at home and school, and thereby avoid much of the fuss, nagging and constant correction that seem to plague your peers. I never understood how they could stand it. Why not just do as you're told? What price an easy life? Looking back, I know that lively young bodies and brains simply aren't designed for such behaviour. Life is too exciting, too interesting not to try to explore it at every opportunity. But back then I spent the day in an agony of frustration until the bell went at half-three and I could escape once more to the peaceful world of home and adults.

I couldn't wait to become an adult, just so that I could be friends with these interesting people who read books, had all kinds of jobs, went to plays and stuff, and didn't spend hours dicking about with the rules of newly-invented games or subdividing into cliques so you had lost track of who was ostracising whom and why by the end of every lunch hour. Children may, in the abstract, trail Wordsworthian clouds of glory, but when you're in a playground full of them, they seem to be toting entire armouries of vicious social weaponry.

But to compensate for your suffering, being old for your age enables you to see further into the brick wall of life than your peers do. I always paid attention in school and did my homework without complaint – yes, partly because I liked it and didn't find it too taxing, but mostly because I could see the point of it. I could see that teachers weren't trying to impart knowledge just for the fun of it. I could see that learning this stuff would pay off. At secondary school, it was easy to resist being caught up in the drive to experiment with sex, drugs and how many nights you could stay out without getting social services involved, not just because I didn't have the big boobs or great hair that membership of such groups required, but because I could see that an array of GCSEs would serve me better in the long run than a plethora of STDs. It is an underacknowledged truth that the sooner you are able to understand the principle of deferred gratification, the better your life will be.

Against that, of course, you have to weigh the fact that your childhood will be, in many important senses, bloody miserable. You won't ever fit in. Even if you buy the right clothes, have the right haircut, deploy the right slang in the right accent, your (putative/non) friends will sense that it's an act. Real children, children who are good at being children, live in the present, not with one eye on the future. To have someone in the group who is running a constant cost-benefit analysis for every action – as good a definition of an adult as any – is both boring and profoundly unnatural.

Furthermore, if you are mature for your age (to quote every school report I ever received), you are likely to turn to books for solace. And although this, again, has unsought, largely academic, advantages, books age you, too. They render it even harder to live in the moment. It is difficult to surrender to an adolescent crush or a first love when you have already experienced a million of them secondhand.

It's good for your ego – by which I mean it pulverises it into little bits and makes you much more pleasant company in the years to come – but at certain times in your life, you need to feel that you and your feelings are unique. Instead, I always knew that anything I was feeling had happened a hundred times before, had been and would be repeated down the generations, that it was neither important nor permanent. "This, too, shall pass," has been my motto from the age of eight. If you are too old for your age, you have a wearying double perspective. Being able to look back on your youth as it unfolds is as sure a way to strip the pleasure from it as you could hope to find.

On the other hand – look at me. Nine GCSEs, three A-levels and totally chlamydia-free. I ask you – who wouldn't swap a few passionate, joy-filled, carefree years for that? Hmm? Hmm.

Obviously, I have been happier since the ghastly years of child-and-young-adulthood have passed. Since people have stopped wanting to go clubbing and started having dinner parties and early nights instead. Since our real and my mental age have started to converge, life has become a lot easier. Plus we're all so knackered by work, children or both that we already like nothing more than to sit over coffees and dream of retirement. Happy days all round.