Yesterday a friend rang. 'X won the fancy dress prize,' she told me breathlessly. 'He went as Robin Hood - I made him a tabard.' 'That's fantastic,' I replied instantly. 'Congratulations.'
We didn't say it, but we both knew what she meant. Little X didn't really win the fancy dress prize. My friend did.
Because even though her children are aged just five and two, she's now in the Competitive Mums Club. I know, because I've been a fully paid-up member from the time my son first toddled through the school nursery gates.
Before you get all PC on me, I don't mean competitive about our children - of course we're proud of them, whatever they achieve. This isn't about them. This is about us.
I'm not sure where this urge to fight them on the playing fields and in the playground comes from, but in my experience it's particularly strong in Working Mothers, anxious to prove that anything the Stay-at-Homes do, we can do too - (and better, actually, so sod off you smug cow, who cares if we're never at the school gates, we can still pull it out the bag when it matters).
The first battleground is inevitably the Mums egg-and-spoon race at sports day, where the gloves - and shoes - are always off.
Next up is the World Book Day Fancy Dress parade. Unless you want your child to endure endless pitying looks from the other mums, you can forget buying a ready made pirate or fairy outfit. In the playground arena, shop bought just doesn't cut it. It's got to be handmade - and it's got to be clever. It doesn't matter how rough around the edges it looks - in fact, the less perfect, the better, because it proves you've Made It Yourself.
I can remember one year spending three evenings (after working all day, of course) hand-stitching my son's Legolas-from-Lord-of-the-Rings outfit, complete with homemade sword and scabbard. I even made him a wig and plaits from wool, and ordered him special elf ears from a movie props company.
He looked amazing - everyone said so. But he lost out on the first prize to a girl dressed as the the Very Hungry Caterpillar - a particularly dynamic feat of needlework.
The following year my little boy went as Iorek Berneson, the polar bear from the Philip Pullman Northern Lights trilogy - which involved copious supplies of white fun fur and endless sewing with white cotton. By the time the damn thing was finished I was snow blind. But all that effort paid off - and my heart was fit to burst as my precious boy walked off with the main prize. I don't even remember what it was now. But we kept the bear outfit.
Then it's the school fete/jumble sale, which brings endless opportunities to show off your talents - particularly in the cake-making department. And don't even think about buying a ready made box of baked goods and passing them off as your own.
I soon learned to cancel any arrangements in the two nights leading up to our primary school's annual fetes - as I would be spending hours on end creaming organic butter and free range eggs to make lighter-than-air fairy cakes (using Nigella's recipe, of course.) Each cake was carefully iced in a rainbow of assorted colours and equally carefully scattered with hundreds and thousands to give them that shabby chic touch. It was all worth it as child after child eagerly handed over their 10ps.
At some point, of course - usually when they leave primary school - all of this becomes less important. You have to find a new outlet for that competitive spirit. But there's always the costumes for the 6th form play...