Make mine a mezcal (with worm and a slice) It's not just that the bar, with its wall of cracked mirrors, tumble of reclaimed furniture, and jukebox left over from the Eighties drinking den it once was, appeals in a Back to the Future way. What really draws me like iron filings to a magnet is the fact that the backlight bar kept by Jenny Beardshall and Melanie Symonds - former television producers - holds the largest selection of mezcal in Europe. They serve no other spirit; tequila is a dirty word. You might have heard of the smaller, finer-featured brother of tequila before (both spirits have the agave plant at their heart). But the likelihood is, if you've come across it, it wasn't a ­pleasant experience. The mezcal we've traditionally been saddled with in Britain has usually had a worm in the bottle and been of a dark, mud-puddleish colour. At Quiquiriqui the bottles shine as clear as crystals in a Swarovski shop window. It's not only at Quiquiriqui that you will find evidence of the spirit's ­onward march, however. In the past 12 months, largely through the efforts of drink distributors Spirit Bear and Amathus, the drink has been ­popping up at bars all around London and beyond. At the Blue Bar at the five-star Berkeley Hotel it is sprayed on cocktails, all the better to allow "the smoky rich aroma to enhances depth of ­flavour in other spirits," according to John Higgins, the assistant bar manager. And Wahaca in London's Charlotte Street as of late last year has a 20-strong mezcal menu, alongside a similar number of tequilas, while London restaurant Lupita is hosting an entire dinner devoted to mezcal on 17 April. If you visit The Experimental Cocktail Club in London's Chinatown for a Smoke and Mirrors, you find yourself gently nodding along to Thor Bergquist, the bar's manager, as he refers to it as the "trending spirit to use." Bergquist finds much to love in its characteristic smokiness. It's a nice substitute for whiskey in classic cocktails that call for a peated Scotch, as the spirit provides the same kind of smoke. And, as a bartender, it's nice to use instead of neutral spirits such as gin or vodka," he says. Unlike those other spirits, production of mezcal is, on the whole, a small-time affair, which partially accounts for its price at around £30-50 for a ­decent bottle.While tequila production is a highly mechanised, multibillion dollar ­industry (Patron, now market leader, reported retail sales of $1.1 billion last year), mezcal is largely handcrafted. Being one of the few drinks left which can accurately be called "artisanal" has also seen it acquire a glimmer of chic. While tequila is produced in ­northern Mexico around Jalisco and uses only blue agave, according to Mexico's appellation of origin laws mezcal can be made from up to 30 ­varieties of cultivated or wild agave in the villages of seven Mexican states: Oaxaca, Guerrero, Durango, San Luis Potosí, Zacatecas, Tamaulipas, and Guanajuato. "In reality, most of the exported stuff comes from Oaxaca and uses an agave called Espadín," explains Jenny Beardshall. The production of fine mezcal,just like fine champagne, has hardly changed in centuries. Agave plants are chosen on the basis of terroir and ­harvested by hand. The piena (heart) is roasted in a rock-lined pit, after which the agave is left to cool until it "looks like a sugar-cane pineapple" says Beardshall. It is then ground, fermented with and distilled in copper or clay pots. This laborious roasting process ­accounts for the Liz-Taylor-after-a-few-gins smokiness. Of course, all mezcals are not created equal There are three different types. Añejo, aged for up to three years (often in oak barrels, which impart flavour of its own). Reposado which is "rested" for anything between two months and a year. And the best, Joven - which we love - which is un-aged, or only for a month or two. Once you age it, you lose some of the mezcal flavour, I think. My ­nodding agreement that I like the Joven best too earns me the nickname "mezcal boy." I can cope with the mocking nickname because I have become an apostle for mezcal; moaning on about it to all and sundry. Because good mezcal forces you to redefine what you think a decent spirit is.When finesse in spirits is discussed, it is usually in terms of delicacy and mellow refinement. Which are, of course, two words that may apply to mezcal. But there are other terms muscling in on it, too, words such as raw, jagged, and, well, bloody powerful. And yet if you choose the right bottle, it lacks for none of the refinement of an XO cognac. And as David Waddington, proprietor of Bistroteque and Shrimpy's and something of mezcal expert, points out, it's a versatile drink to keep in your cupboard at home, too. We're drinking Mezcal Amores, light, subtle flavoured, as an aperitif, and Los Danzantes Reposado is super after ­dinner, with chocolate. That's the thing about mezcal, to most of us it's a new taste, one without the atrophied customs that accompany other spirits like ancient butlers, making sure you behave well with them. Waddington says there is only one rule: "never "shoot" mezcal" he says. Unless you have a broken heart, that is, in which case it's a sure-fire cure.