A sip here, a sip there. We are going on a three hour adventure across the world's greatest coffee city. No, it's not Rome, New York or Sydney. The tastiest caffeine is to be found right here, in London.

A few years ago, it was all so different. There was a choice between a Nescafe or a burnt espresso served by a spotty teenager in one of the big chains. Monmouth made waves when it started roasting its own beans in London. It became a firm favourite at Borough Market.

But something big happened in 2009. Gwilym Davies – a Brit – became the world champion barista. He had been serving coffee to lucky locals from his cart at an east London market, and soon opened up a concession in a nearby clothes store.

The world took notice – the London coffee scene had finally come of age. Since then, dozens of exciting little independent coffee houses have opened across the city. And we'll visit at least five of them.

The idea is that we'll order a round of espressos, have a few sips (no, don't down the whole thing, unless you can handle a five-espresso-day!) and talk about what makes for a good coffee. In some of the locations, there are different beans, so we can share and compare.

You'll never visit Starbucks again.