From where I sit: Northern exposure

They say the best way to handle nerves when public speaking is to imagine your audience naked, but that wasn't much help when I gave a talk at the British Naturism winter bash somewhere in the north of England.

Yes, it was indoors and centrally heated; and yes, I did observe the dress code - it would have been rude not to. In short, I had my first naturist experience on stage in front of about 80 naked strangers. So the next time you feel exposed on the podium, worrying about your equipment letting you down or whether you've got everything covered, just consider: things could be a good deal more taxing.

I was there to talk about the history of modern sun worship, which I'd covered in my book Sunshine: Why We Love the Sun, a cultural history published last year. The naturists were the first social sunbathers, the first to turn what had been a medical necessity (to cure tuberculosis or combat rickets) into a way of life.

Before about 1930, there was no real distinction between "sunbather" and "nudist". Until then it was illegal to sunbathe in public (even semi-clothed), apart from a few designated beaches. The nudists were devoted to healthy living and the great outdoors, and were simply sunbathers with attitude, fighting for things we now take for granted in our relationship with the Sun.

I was there to celebrate this contribution and talk about my adventures writing the book, such as working my way through the first 40 years of Health & Efficiency magazine in the British Library. I had to consult the publication at a "special" table reserved for "special" material, getting "special" looks from the librarians when I collected it.

Yet there's nothing even remotely titillating about this publication (which started out as Vim: a Magazine for Physical Culture in 1900). No one gets naked until about 1933, and even then it's all very earnest, moral and stodgy - like the Boy Scouts, but with nowhere to sew the badges. There were even regular homilies on the dangers of self-abuse, which is ironic given H&E's later reputation among men of a certain age and particularly galling for me, bathed in moral opprobrium in the British Library's Smut Corner.

This and more I shared with an attentive audience, exposing much more than just my white bits. Accidental naturism is instant anthropology and analysis (and far cheaper than the couch). Here is "unaccommodated man", the thing itself. Discard the lendings of custom and culture and you are compelled to recognise the motley patchwork of insecurities, vanities and neuroses our tailored comfort blankets usually disguise.

Combining ill-prepared examination with public nudity, this was a wide-awake anxiety dream of my own making. And yet, I actually felt less nervous than I have done at more conventional gigs. Nakedness, like death, is a great leveller, and there's a reassuring empathy in collective vulnerability.

So I remained disrobed for the rest of the weekend, even for the "naked disco" that evening, where, I was told, "we let it all hang out" - an event to separate the men from the boys (and the girls). I lived to tell the tale, returning to the land of the dressed a bit like Gulliver from his travels, unable to look at my fellow clothed bipeds in quite the same way again.