Rubber sole

The material world

Unless you were very young, still lived with your mum, were in your forties, or smoked strange cigarettes, sensible sandals probably did not warrant a place in your wardrobe. Flip-flops? Yes. Moccasins? Maybe. But open-toed Cornish pasties?

Then, in 1990, style magazine The Face featured Kate Moss with thick- soled flatties, and Birkenstocks became hip. From Milan to New York, London to Paris, no catwalk was complete without at least one model padding about on a pair of lilos with straps.

But these aren't just comfy shoes given a makeover. As any devotee (Madonna, Keanu Reeves and Jerry Hall, among them) could tell you, their sandals are ecologically sound. Only the unshod can feel more virtuous.

Birkenstock footwear is made from leather bought from countries with restrictions on chemicals that harm leather workers.They have recyclable cork soles from Portugal and are strengthened with natural latex from Malaysia. Owners might also boast that the dyeing process involves vegetable tans (thus avoiding tree loss), and the factory in Bad Honnef, Germany, generates its own gas and electricity, so that there's no need to feel guilty about depleting the Earth's natural resources.

What's more, most parts of the sandal (or closed-in shoe version) are reparable, which is bad news if you get bored with them or, worse, they go out of fashion.

The Birkenstock family became cobblers at the turn of the century, but it wasn't until 1965 that grandson Karl came up with his revolutionary "footbed" idea. This is a moulded surface created to match the natural contours of how your foot should be. This brings us to a rather controversial study published in the Journal of British Podiatric Medicine. According to chiropodist Phyllis Jackson, the Celtic foot - as possessed by the Scots, Welsh and Irish - is generally slimmer than the broader, Teutonic foot (those of Germanic origin). Since British shoe manufacturers base their designs on the Teutonic model, this could be why the Celts suffer more with their feet. And foot problems cost the Government pounds 44 million a year, with 70 per cent of them arising from ill-fitting shoes.

Indeed, the Society of Chiropodists and Podiatrists says that nearly one-third of women are prepared to suffer corns in the pursuit of style (compared with 14 per cent of men). Stilettoes are the worst culprits -the only reason they stay on is because they have to be smaller than your normal shoe size. Women have generally stopped buying them, but less because they're uncomfortable than because hemlines changed.

This, of course, suggests that, had Kate Moss not helped make Birkenstocks desirable, we might not have bothered, either. But the very young, the very dull and those who live in communes would still tell us how nice they feel to wear