You can cancel your 30th birthday party, Kate, but you can't hide The Duchess of Cambridge will hit the big three-oh on Monday, and if you were wondering what to get the girl who has everything, the answer, it seems, is absolutely nothing at all. Close friends have been told to forgo gifts in favour of a donation to one of the five charities she recently became a patron of, and the obligatory 30th birthday party seems not to be going ahead. Those of us keen to see the Duchess dressed as Alexis Colby at the Eighties-themed bash that Prince Harry and her sister, Pippa, were said to have planned for her, will be disappointed to hear that Catherine will instead be celebrating the birthday with a "low-key and private" event. Was the Royal family's party spirit removed along with the Duchess of York? Did Catherine promptly cancel the event - which was even said to include such civilian activities as karaoke - after seeing her new husband attempt to do the "swag dance" at a recent charity event? Or is it simply that turning 30 is not as landmark an occasion for Catherine as it is for the rest of us, given that she has been that age - possibly even older - ever since she met her husband at university back in 2001? Let's face it: the Duchess was a duchess even when she was plain old Kate. When she met Prince William she was 19 going on 30, giddily beautiful but wonderfully mature. Yeah, Catherine did walk down a university catwalk dressed in a net curtain. Granted, she also turned up at a charity roller disco in neon spandex. And it was once reported that she had attended a film party called "Rabbit Fever," where female guests were given goodie bags containing, ahem, bedroom aids shaped in the form of the small mammals. But the Duchess has never seemed to like a party. She celebrated her 26th with a "small cocktail" do at her Chelsea flat, her 27th and 28th with a dinner at her parents" home in Bucklebury, Berkshire, and her 29th with "close friends" in North Yorkshire. The "low-key and private" event that is her 30th will probably involve a takeaway, Bridesmaids on DVD, and an early night. Oh envy - be gone! The Duchess has got the looks, the clothes, the house, the Prince and now, to top it all off, the ability to pass her 30th birthday without ne'er a sideways glance at it. How is this fair? What is her secret? And what alignment were the stars in when she was born on January 9, 1982? Turning 30 is a special kind of horror. It is a special kind of horror that only women can really know, because men do not have it drummed into them from an early age that their fertility will drop off a cliff at the age of 35, their ovaries turning to shrivelled prunes as desiccated as the Gobi desert. It is not the first landmark birthday that we face, or even the second, but it is the first one we "celebrate" without a sense of semi-adolescent immortality about us. At 18, you think you will live for ever. At 21, you don't care how long you live as long as you get off with the fit bloke with a rowing scholarship doing his finals. At 30, you realise that you have probably seen over a third of your life and that the fit bloke with the rowing scholarship was a cad with an IQ less than his inside leg measurement. I know I am not alone in feeling this particular kind of misery. Do you know how I spent my 30th birthday? Crying, mostly. I fell over running for the bus, ripped my Primark skirt and a great deal of the skin on my knees, and had a little weep outside Pret A Manger because I had to remind my boyfriend at the time it was my birthday, and only received a perfunctory text message for my troubles. I forced myself to have a party the weekend after, at which a series of people said things to me such as: "The clock is ticking," "Look, you're getting crow's feet!" and, my favourite: "It's all downhill from here." But it wasn't. It really wasn't. Turning 30 is a bit like an arthropod shedding its exoskeleton - not particularly pleasant, but rather liberating once it is done. So in a funny sort of twisted way, I feel a bit sorry for Catherine being able to treat her 30th as just another day, and not the rite of passage it is. Then again, perhaps she's simply choosing to ignore it. In which case, she should know that it will be absolutely fine. And that being 31 is bloody great.