In what is bad news for Ed Miliband and David Cameron and terrific news for Boris Johnson, blonde hair for men has officially been declared A Thing For 2015 by style watchers.

No, really.

As ever, the fashion arithmetic is pretty shaky, but if you're interested it goes something like this: take the handful of male models who recently took to the catwalks with peroxide crops, add an Instagram picture of 15-year-old Brooklyn Beckham showing off the same - "Makeover alert!" trilled website Hollywoodlife when the hot news broke - and multiply the result by the number of people who care about such things and on the other side of the equals sign you'll have the word "Trend".

If you want some figures which are slightly more solid and considerably less made-up, I have those too, courtesy of market intelligence agency Mintel.

Its Hair Colourants UK 2015 report finds that sales of some hair dyes have tripled over the last year, with the greatest uptake being among male buyers. The research also finds that a third of men aged between 16 and 24 have coloured their hair themselves in the past year. Conclusion? This is a real, bona fide trend. The fashion sums are correct for once. That's not to say that all this dye is designed to turn hair blonde. There might be some men who are dying their hair pink or green or purple. But it's a safe bet that most of it is at the Kurt Cobain-meets-Billy Idol end of the colour spectrum. I mean nobody's going to want to look like Mick Hucknall are they?

Dyed hair and mathematical equations being the subjects at hand, I was going to make a joke here about square roots. But I'll leave it. Instead I'll just say that I heartily approve of all this: getting your hair dyed blonde then dressing in black so you look like a pint of Guinness with feet is a male rite of passage I am keen to encourage.

So is doing the dying yourself. I have fond teenage memories of afternoons spent crouched over a sink in the school toilets, a bottle of neat peroxide in one hand, a picture of Rutger Hauer in Blade Runner in the other. Yeah OK, so it was actually Limahl from Kajagoogoo. I admit it. The point is my DIY blonde ambition knew no bounds - other than the ones my mum imposed when I turned up at home with my hair the colour of parsnip.

Yes, parsnip. You see that was always the trouble with my (many) attempts at going blonde. I never quite managed it. In about a decade of trying - let's say between Wham!'s Club Tropicana and Radiohead's Creep - I only ever ended up with various shades of root vegetable: carrot (Sun-In, plus hairdryer), swede (Sun-In, plus a week in Greece), and potato (Sun-In, plus hairdryer plus two weeks in Greece). By the time grunge ended and I turned 30, I had decided to give my hair a rest. It needed it. Now, while I'm glad that blonde is back, I think my dying days really are behind me.