Rather than violate the civil liberties of a law-abiding British citizen I would prefer that Gwilym Davies voluntarily strap a GPS tracking bracelet to his ankle. But if the 2009 World Barista Champion refuses to help us trace his movements via GPS or constant twitter updates I may soon have to ask my man at MI5 to slip a microscopic satellite-tracking particle into Gwilym’s morning coffee. When we discriminating cafenatics are on the loose in London we have a right to know where and when the champ is pulling espressos.

Why has it been so difficult to pinpoint his whereabouts? For years now, Gwilym has not plied his craft in a coffee shop with a fixed address and fitted plumbing. That would be too restrictive for a free-spirit who lives in a houseboat. He developed his championship form working irregular hours at a freestanding cart parked at Whitecross Street food market (“Pitch 42”) on weekdays from 8ish to 2ish and behind the Columbia Road flower market on Sundays at roughly the same hours. His schedule was made more uncertain by his winning the World Barista Championship (WBC) in April 2009. A rock star in the coffee world, he’s invited to Italy so often he may have to change his name to Guglielmo. And now he’s rolled into Shoreditch with yet another cart. Prufrock, as the sleek and polished trolley is known but not labeled, is positioned inside the fashionable menswear shop Present (140 Shoreditch High Steet – see map).

With the cart at Present Gwiylm has rolled out the prized Nuova Simonelli piston espresso machine he won at the WBC. Piston espresso machines, unlike most pump-driven ones, are fitted with manual levers that need to be pulled down by the barista to build pressure and force hot water through the coffee grinds. The term “pulling” an espresso derives from this action.

The espressos, lattes and cappuccinos prepared with a piston machine are not necessary superior to those made with a pump machine. In fact, because these manual machines are so difficult to operate the results are often disappointing. Struggling to get his espresso and steamed milk the way he wanted and hoping to learn from his missteps Gwilym recorded all the variables of his failed attempts – dry weight, total time, liquid weight, etc – on a hand-written chart. This proved counterproductive. He is a coffee geek, sure enough, but not a charts and numbers coffee geek. “Stop thinking so hard,” advised his roaster, Annette Moldvaer of London’s Square Mile Coffee. “Just make a nice coffee.”

He listened and he did. Not every espresso is the same. One can be heavy and chocolatey; the next, lighter and fruitier. But it is this very mutability that I find most appealing. Whereas competition baristas like Gwilym are judged for the consistency of their drinks and presentation, at Present he and the star baristas who operate the Nuova Simonelli in his absence are embracing an inconsistency and imperfection dictated by a fiddly manual machine. Every result is a discovery; every cup, unique. The ultimate reward for Gwilym is found in the quiet of the piston machine. There is no electric pump making noise. For the first time he can hear his world champion espresso fall into the cup. At Present, you can hear it, too.