It was my fortieth birthday a couple of weeks ago. FORTY, for fuck’s sake! I am now a 40 year old woman! How on earth did that happen?

Oddly, I wasn’t in the least bit concerned in the run up to the day. No denial, no keeping it quiet, no plans to pretend, like the mum in Judd Apatow’s hilarious movie ‘This Is 40’, that I will remain 39 forever, no telling people not to make a fuss. That’s not my style: I like MAXIMUM fuss to be made of me on my birthday, and always make a fuss of people I love on theirs.  Any excuse for champagne, frankly. No, I embraced it utterly, and planned a big grown-up garden party.

As the Significant Birthday approached, people kept saying things along the lines of: ‘Ooh, the big Four-Oh, how are you feeling about it?!’ and I was then able to spout my ‘Theory of Being a Forty-Year-Old Woman in 2013’. Which goes something like this. There has never, in human history, been a better time to be a woman. There’s still a long way to go – there’s appallingly bad shit and inequality and unfairness and misogyny and sexism still going on around the world to women and girls – but nevertheless. In particular, there has probably never been a better time to be a woman over 40. Or an Actual Grown-Up, as I now think of what used to be called Middle Age.

Just look around you, at the musicians and actors and models, the business leaders and entrepreneurs, the writers, journalists, politicians and sportspeople. There are an awful lot of Actual Grown-Up Women among them. Some of the coolest, sexiest people in the world are now over 40. Kylie’s 45 (KYLIE!), and Madonna was 55 last week, for goodness’ sake. Jennifer Aniston is 44; Samantha Cameron and Susanna Reid are both 42. Paula Radcliffe was born the same year as me. Karren Brady is 44, and JK Rowling is 48. Cameron Diaz is a year older than me. Yeah, really! The original supermodels are all in their mid-40s. Women aged over 40 are at the top of their game: mature, confident in their skin, look frickin’ amazing, and have an attractive sheen of experience and wisdom.

In short, when I think of myself as a 40-year-old woman, I don’t think ‘Shit! I’m over the hill! I’ve done nothing with my life! In my advanced years I must cut my hair unflatteringly short and wear crap clothes and ugly shoes and no make-up and inexorably trudge down the path to old age and incontinence and death!’ Rather, I think this: Wow. This is totally going to be the best decade ever! This is the decade when I will accomplish my dreams and achieve my potential. Now my children are no longer tiny and totally dependent on me, now I have something approaching a life of my own again, it’s going to be amazing. This is where I get to be utterly myself, where there are no barriers. apart from my own thoughts, to business success, finishing that novel, being thin, being comfortably-off, being happy, and being fit and healthy.

That’s the most personal thing, right there. The healthy bit. My thirties weren’t all they were cracked up to be. Apart from giving birth to my two darling children, I was basically stressed, broke, anxious, depressed or having panic attacks for much of my thirties (and twenties, if we’re being honest). And then my late thirties were spectacularly crap thanks to my Cancer Experience. You know how much I hate the language of cancer – the battling, struggling, fighting, surviving stuff – but as I approached my 40th birthday I actually felt euphoric about having reached this ripe old age because (and you may never hear me use this word again) I survived. I got this far. And so my party was a chance to say thank you to (almost) all the people who supported me and DH through it, and to celebrate having actually got to 40, which looked like a distinctly shaky possibility three years ago when I was diagnosed. 

Still, I do wonder when I’m going to feel grown-up. Does that ever happen? When I was younger, my mum would say she still felt 18, and I never got what she meant, until recently when I realised that in my head I am basically still 22 and feel no more emotionally mature, stable, sophisticated or cool than Taylor Swift. I am hoping that at some point I will know my limit on white wine, stop drunk texting and tweeting, re-heel my shoes on time, learn to play golf, or tennis, own a fancypants coffee machine, have regular manicures, and never run out of bog roll or milk. That time is not now.

My birthday itself was perfect: the Royal Academy Summer Exhibition (my annual art indulgence) with DH and the kiddies, and then champagne afternoon tea at my new favourite restaurant, Balthazar, with the surprise addition of my mummy, which reduced me to tears. DH bought me a stunning grey snakeskin Michael Kors handbag and, from the kiddies, a gorgeous gold ‘Pinchy’ name necklace, made for me by a stroppy little Polish man in Hatton Garden (His phone call alerting DH to the completion of the commission was a terse ‘Hello? Pinchy is Ready’. Dial tone). Then a takeaway and more champagne at home with our best friends, which accidentally got a bit drunken. Then an indulgent lunch the next day at Le Gavroche with my wonderful parents, and sis and brother-in-law, who gave me the most beautiful gold bracelet. Mama and Pops had created an amazingly nostalgic Aspinal leather photo album with photos of me from newborn to now, embossed with ‘Maja – the first 40 years’ on the front. (Mummy said she was going to put 1973-2013 and then realised that it would look like I had actually died…) 

So I didn’t really need the party I had planned. But what a party it was. We cunningly shipped the smalls off to our dear friends’ house with an all-night babysitter so all the kiddies could have fun together and all the adults could stay at ours and have a lie-in the next morning.  We spent all day dressing the garden: hay bales covered with colourful fleeces, Chinese lanterns in sorbet shades, fairy lights, and bunting. At 8pm, guests started arriving and under the gazebo there was live music – a guy and a guitar, and his girlfriend singing Kings of Leon tracks beautifully – to accompany prosecco, and canapes made by my mummy and best friend. We even had catering – a deliciously meaty South African barbecue – and then the party really got started, with DH manning the ‘Marisco Disco’ (ie a playlist on my iPad attached to a proper sound system kindly loaned to us for the occasion).

Everyone had dressed up. The wine flowed. I danced on the patio under the fairy lights all night, with my best friends and my family (my mum and dad have got some stamina, I can tell you). I can’t remember the last time I did that. Being whirled around by gorgeous boys for hours on end was quite marvellous. I lost count of the number of times we had Robin Thicke’s ‘Blurred Lines’ on, with 46 people shouting ‘You know you want it, you’re a GOOD GIRL’ repeatedly. My sister (dressed as Chris Lowe from the Pet Shop Boys circa 1988, just because she knew I would love it) and brother-in-law presented my birthday cake: delicious chocolate brownies in the shape of the number 40, each with a candle. One of my oldest school friends had flown over from her home in Malaysia just for the weekend, just for me. Another lovely friend came straight from his flight from Ireland and arrived at 11.30pm to share my celebration. Almost everyone had booked a hotel room, so they could fully commit to partying. I was spoiled with gifts of every major champagne label under the sun, and some beautiful jewellery, and compliments on my last-minute dress, and many, many hugs and kisses. The old Salisbury gang was back together for the first time in years. My uni chums were there, and my mummy friends. Everyone had a ball.

The last guests left or went to bed at 4am. (The neighbours kindly asked us to take the music inside at 1am.) And when everyone else had gone, I stayed up for a bit by myself to savour it all and quietly open a couple of pressies. To soak up the last vestige of party atmosphere, and cement my memories. My jaws ached from smiling. My knees and toes were killing me from dancing in heels for seven hours. I’ll never forget it. It was perfect. 

Being born in 1973, we’ve had a few 40th celebrations over the past year, and more special ones to come in the next couple of years among my closest friends. It does feel like a really significant birthday, a real milestone or marker in one’s life. Some people dread being 40 as it approaches, and I totally get that. It’s a natural trigger for quite a lot of self-examination and life assessment. I say: embrace it. Enjoy it. Celebrate it. Mark it, as noisily as possible with as many people as possible and as much champagne as possible. And when the hangover has abated, and life, somewhat surprisingly, gets back to normal, get on with the business of living, and loving, and start planning your 50th birthday celebration. I’m thinking Vegas…