If you're anything like me, you probably find the global dominance of the Subway sandwich chain bewildering. There are now 32,046 Subway branches in 90 countries, making it the biggest fast-food purveyor the world has ever seen. But for why? The outlets are nothing but tiled slots with an interior design suggestive of a post-apocalyptic New York: the subway map, brownstones and Brooklyn Bridge, seared like the silhouettes of atom bomb victims into the shit-brown decor.

Many pundits attribute the success of the chain to one simple perception - Subway is the healthy option. In marked contrast to the super-sized food fascism of the beef-farting, chicken-black-hole-of-Calcutta merchants, some joker in Florida actually lost weight on a Subway-only diet. Needless to say, he's been a poster-boy for the chain ever since, a sort of Horst Wessel of hearty Italian bread. I'm not arguing with the idea that you can eat healthily at Subway, but then you modulate your nutritional requirements just as effectively at any corner sandwich shop.

Chain gang

No, the secret of Subway's success rests, in my view, on two things alone: first, there's the very fact that it is a chain, offering a modular eating experience that can be simply replicated from Bloemfontein to Bangor. Nothing succeeds like ubiquity, and the more Subways there are, the more the sandwiches they serve approach the Platonic ideal. Then there's the store-baked bread. I'm not sure what the actual mechanics of this are, but most probably the bread arrives in the form of pre-kneaded and portioned dough, and is simply popped in the ovens. No matter: the by-product is that warm, yeasty stench that wafts from the door of every Subway, selling the scurrying punter the idea that here be Mama.

Once you're inside, the sight of the demonstration sub-breads stuck on a board - wheat, Italian herb, honey oat, hearty Italian and Italian - is queerly reminiscent of coprolites in a dun cave; the sandwich-makers, meanwhile, their hands gloved in translucent plastic, might be archaeologists of the present, deducing from their steely bins full of bacon shards the constitutive elements of Homo Britannicus's diet circa 2009. My 12-year-old adores Subway, but as he possesses all the gastronomic finesse of a half-starved bull calf, that says nowt about owt. Still, I dragged him out to one for lunch and we both had the "meal option": a six-inch sub of our choice, together with a cookie and a fizzy drink, all for £3.49.

Special cocktail

I say "a" fizzy drink, but Subway, with its economies of scale, can offer unlimited fizz as part of the deal. My boy happily mixed his special cocktail, one part Sprite to one part Coke, then topped up the 16oz bucket with Fanta. "How is it?" I asked. "Too Spritey," he grimaced. He had the same sandwich he always does: bacon, lettuce and cheese on honey roast, then sat there giving me the sort of "healthy option" guff that would doubtless enrapture Subway shareholders.

I made my way through my own chicken pizzaiola sub with rather less enthusiasm. There was nothing offensive about its tender chicken-breast strips, pepperoni, cheese, tomatoes and tasty marinara sauce, but that was because it was so . . . well, nothingy. It wasn't the flavours, it was the pappy consistency of the bap and its contents, which looked like it could have been premasticated.

There was a queue of little chicks waiting to be fed this easy-to-swallow fare, and I asked a young British Asian man what he saw in Subway. "It's like a pick'n'mix thing," he said. "Mind you, I only come in this one on a Friday when it's the tuna option." Next I turned to the Dutch couple sitting next to us: did they have Subways under the Netherlands? "One or two in Rotterdam," the male Cheesehead said. "But, honestly, we don't go in for this kind of thing."

“No," his Edam concurred. "Everyone gets free coffee at work, and people just take a bit of cheese and bread in with them for a snack at lunchtime, so we don't need places like this."

Don't need! Poor, benighted fools - no wonder they reached the zenith of their world influence in the 17th century. Without a keen understanding of how to parlay cheese and bread into unlimited economic growth, these burghers have no place in the modern world.

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