Root-to-fruit. Farm-to-table. Bean-to-cup. Chances are, you've come across at least one of these terms on your travels around London's cafés and restaurants. The reason is simple: in the age of information, the more we learn about our food and drink, the hungrier we seem to be for knowledge.

A happy knock-on effect of this hunt for expertise is that – in general terms – the more we care about our food and drink having a traceable, ethical supply chain, the better it ends up tasting, and the more we're likely to care about it.

It's the reason why, in 2017's London, you might go into a café and order a flat white with espresso from Nicaragua, because you think the "almond, chocolate and orange zest" tasting notes sound more up your street than the beans from Ethiopia or Indonesia. It's the reason why you might be happy to pay £8 or £10 for a bag of coffee beans you know have been imported from a farmer at a fair price. It's the reason you might own an Aeropress or a V60 filter, and why you consider the act of making a coffee as a ten-minute job, at least. And it's catching on.

But, as much as you know about how best to enjoy what happens when ground beans meet hot water, steam or hot milk, how much do you really know about how it gets here in the first place? We've enlisted the help of some coffee brands, big and small, who are building their business models in search of not only better coffee, but better ethics, too.

It involves working directly with farmers not only to treat them fairly, but to make sure their products are the best they can be, and are a genuine reflection of the environment they're grown in. Because the more we understand about the coffee we're drinking, the more we enjoy it. So sit down, grab a cup of tea (just kidding) and read on…

How coffee arrived in London

It might surprise you to know quite how far back London's history as a city of coffee lovers goes. One man who's in a particularly good place to tell its story is Geordie Willis, creative director of wine merchant Berry Bros & Rudd. While this may seem like a total non sequitur, there's a reason he's in the know: as a direct descendent of the Berry family, it was his ancestors who set up not only one of the first coffee retailers in London, but one of the first shops, full stop. While most trading was done at market stalls in 1698, the Berry family set up a bricks-and-mortar site on St James's Street – the same one that's there today.

They started adding cloves, spearmint and wine to coffee

"The thing that a lot of people don't know about us is that actually a third of our existence has been coffee, tea and spices," Willis says. "We were what was referred to as an 'Italian grocer'. We were never a coffee house in the traditional coffee-house form – we weren't serving coffee in the shop – but we were selling it, along with spices, tea and other provisions to the coffee houses, predominantly the coffee houses of St James's and the surrounding areas."

Coffee was already popular with the hoi polloi of London at the time, but it would be a while before the coffee houses of Mayfair became the cafés we know today. "The coffee houses would have been spaces with large cauldrons of eight- to ten-gallon cauldrons bubbling away," Willis says. "Coffee was very bitter at the time – they started adding things into it: cloves, spearmint, wine sometimes, to make it a bit more palatable."

Berry Brothers & Rudd's scales

Berry Brothers & Rudd's scales

Coffee was still a relatively new and untested drink, although it was looked on favourably by those in charge. "Any hot drink that involved boiling water was safer; the government were behind coffee because it was certainly less damaging than alcohol at the time," Willis says.

But coffee wouldn't be a drink someone could easily make at home for a while yet. "It was harder to make it at home even after the coffee mill came through," he says. "Making coffee was something that was predominantly in the coffee houses; tea was easier to do at home.

"Around London, the various different coffee houses were being frequented by different types of people – it might have been the wigs in one place, it might have been lawyers, politicians and so on. They were these convivial places where people would meet and talk."

"They were less rowdy than the taverns; plus they were warm, which was quite important at the time – people would come in and shelter. They were quite expensive – they were a penny to gain entry at the time, so they weren't necessarily for everyone – but people would congregate and talk about ideas. The ballot system – that came out of the coffee houses. The newspaper – that was from the pamphleting that surrounded them."

It's a hell of a legacy for a hot drink. But places that serve coffee have stood as meeting places and cultural centres ever since the product first started being brought to the West from Yemen and Turkey in the 1500s. While from the height of the British Empire until fairly recently we traded in volume and tried to keep costs down at all times, consumers are waking up to the importance of seeking out better trading standards.

That early history shows how London came to love coffee, but it's only recently that we've come to truly appreciate how complex it is.

"The roastery scene when we first started in 2002 was a different world," says Nicole Ferris, managing director of Climpson & Sons, a coffee roaster, retailer and café in Hackney. "There wasn't much of a 'scene' back then, but Monmouth, Tea and Coffee Plant, Square Mile and a few others were on our radar."

Since then, though, it's a different story. "The coffee market is becoming more defined by discerning individuals who place high values on taste and distinction," she continues. "Just like the increase in popularity of craft beer, natural wines and fine foods, people are turning to independent, specialty coffee shops. People want to know where their coffee is coming from; they're asking more questions and are more demanding on cafés and roasters to be transparent and share their knowledge."

"According to Allegra, the total UK coffee shop market is now valued at £7.9 billion," says Ferris. "It's on track to exceed 30,000 outlets by 2025, and to break £15 billion in sales over the next decade."

Even now, 300 years after the West fell in love with coffee, it's still on the up.

Coffee trading

Coffee, as with much of what's grown and traded in the tropics, has had something of a chequered history in ethical terms. It's traded on enormous scales, and farmed largely in developing communities.

But in recent years, there's been a shift. "Coffee, like corn or sugar cane, existed in a world where the people were largely irrelevant to the end consumer," says Origin Coffee's Joshua Tarlo. "The farm-to-table movement has really opened people up to de-commodifying their food."

Tarlo is on an annual sourcing trip to Kenya as he speaks – as Origin's head of coffee, he ensures the brand has as much direct with the farmers the company works with as time and logistics allow.

"In Nicaragua, we work with one family to get thousands of kilos of coffee," he says. "Here in Kenya, we need to work with almost a thousand producers – the farms here are incredibly small so it takes a village to make a latte. The size means that it gets almost impossible to visit all the farms, so what we do is visit the mill where the coffee from all the farmers is processed. We meet with the president of the cooperative they belong to, talk to a few of the farmers if we can, chat with the agronomists who work with the farmers and get a sense of the community."

Climpson & Sons runs along the same lines. "Ian [Burgess, Climpson's founder] started roasting in a shed for the market stalls in 2003," says Ferris, "and he began roasting for wholesale in 2005. Back then organic and Fairtrade were still prevalent, but the move towards direct trade and paying a higher price for quality coffees has been more noticeable."

"We work with trusted partners at origin to ensure producers receive fair prices," Ferris says, "and we seek to develop ongoing relationships in buying from many of the same farms each year."

Origin and Climpson are both rooted in the new school. They're the kind of small-scale (initially, at least) independent roasters and retailers that have created the thirst for quality, and often single-origin, coffee in London. But, while they can leave their stamp on coffee culture, it takes big players to join in to effect change on a huge scale.

Lavazza, one of the world's biggest coffee retailers, is in a position to do just that: "We feel it is essential for coffee roasters to maintain a strong ethical stance when sourcing beans," says Mario Cerruti, the brand's chief sustainability officer. "It's up to us to be leaders and help elevate the industry to higher standards."

While Lavazza's scale of trading makes facetime with all of the brand's partners somewhat unrealistic, the company nonetheless keeps close tabs on its trading: "We work very closely with our coffee farmers, ensuring high quality and ethical standards are met for each one of our producers," says Cerruti. In 2001, Lavazza was a founding partner of an organisation called The International Coffee Partners.

"The aim of ICP is to make small coffee-growers more competitive," says Cerruti, "to develop their entrepreneurial skills, and improve their living conditions and their work by promoting more sustainable farming practices, protecting natural resources, as well as boosting the building of growers' coordination networks."

It's exactly the kind of change that was desperately needed. While in London we have enough choice that we can seek out the kind of small-batch coffee that's made according to our own exacting principles, it doesn't make up the majority of the coffee traded around the world. Put simply, every coffee company big or small, is responsible for making sure its way of working benefits its farmers as much as itself.

Single-origin and coffee geography

The arabica strain of coffee bean is said to have been discovered in Ethiopia in the 11th century. Since then, it's been transported around the world, and centuries of growing have created coffees with entirely different flavours based on where in the world they're grown. "Coffee needs very specific conditions in order for it to grow," says Climpson's Nicole Ferris.

"Because of this, coffee only grows close to the equator, between the Tropic of Cancer and the Tropic of Capricorn. This is known as the coffee belt. The regions in between this belt provide ideal soil quality, temperature, climate and topography. Coffees tend to have characteristic tendencies based on where they are grown: the provenance of the coffee, including seasonality, altitude and other growing conditions will affect the outcome of flavour."

While it's far from simple, the flavour of a coffee bean after it's processed, roasted, ground and made into a hot drink has a lot to do with where it hails from.

Climpson & Sons coffee

Climpson & Sons coffee

"The unique customs of the people who grow the coffee, the soil it's grown in and the unique climate of each farm offers massive diversity, but there are trends from one country to the next," says Origin's Joshua Tarlo. "Kenyan coffee tends to be winey, fruity and sweet, while Colombian coffee can be citrusy and floral."

Ferris expands: "Coffees from South America are known for their sweetness, big body and medium-to-low acidity. Molasses, hazelnut and chocolate are common tasting notes from this part of the world. From Asia, you might find earthy, spicy, full-bodied characteristics – savoury and tobacco notes mixed with a cinnamon and nutmeg character. East African coffees are regarded as some of the most complex in the world. They are grown at high altitude, which results high acidity. Here you might find bright citrus, blueberries, tropical fruits, black tea, berry-like floral notes, dried strawberries, blackcurrant, stone fruits and bergamot."

While to some, coffee might just taste like coffee, an increasing number of people are looking to speciality coffees for their complexity, and single-origin – coffee that can be traced back to a single region, or even a single farm – is hugely popular. It's not only for speciality roasters but also for brands like Lavazza, which is releasing a new range of single-origin coffees this August. When you consider that the company's founder, Luigi Lavazza, is credited with inventing blended coffee, that's a big move.

soil quality, climate and altitude all have an impact on flavour

"There are other elements that have a great impact on the quality of a cup of coffee," Ferris says, "such as soil quality, climate and, most importantly, altitude. This is referred to as 'terroir' and encompasses all the growing conditions that have had an impact on its unique characteristics."

Washing, processing and roasting coffee

Like chocolate, coffee's raw material doesn't bear a particular semblance to the finished product you're used to. "Coffee 'beans' begin their incredible journey as the seed of a coffee cherry, found on coffee trees. The unripe cherries are green and ripen to a deep red, orange or bright yellow colour depending on the variety," says Ferris. "Before roasting, processing is the most important stage when determining flavour in the final cup."

"The farmer grows the coffee and hopefully picks it when it's nice and ripe-looking – like a dark red cherry," says Tarlo. "Getting the fruit off the little seed inside – which becomes the bean we grind and brew – can massively change the flavour."

This is where it gets complex. It's not as simple as just roasting the beans, nor is it only a coffee bean's geography that determines the flavour of the resultant cup of coffee.

"Processing is essentially the chosen method of removing the seed from the cherry," says Ferris, "and there are three ways you can do this – the washed method, the natural method, and the pulped-natural method – each of which imparts different characteristics on flavour."

London's coffee history

A sign at one of Origin's partner farms

So how does it differ? "There's the oldest way, called the natural process, which just means leaving the cherry in the sun for the fruit to turn into a raisin, where it separates really easily," Tarlo continues. "Or you can use machines to force the bean out, which we call the washed process. That old way tends to make a vibrant fruity cup and the machines tends to make something more round and balanced in flavour." Pulped-natural fills in the blanks, removing the outer skin from the cherry but leaving on the pulpy 'mucilage' around the bean.

Origin is so confident that its customers can keep up with these technicalities that it's just begun to release sets of single-origin coffees, from the same farm, whose beans differ in terms of their processing, so that consumers can see the differences for themselves. "It's pretty wild how different processing makes such different cups," Tarlo says.

"The washed variety is really round, balanced and floral. The natural is vibrant and sweet, knocking that delicate floral business out and just tasting like the ripest berries around. The pulped natural is the 'Goldilocks' coffee for a lot of people, balanced between the two and keeping the light florals with the booming sweetness. The series is a pretty great way of not just seeing how different coffee can be but also getting to know what you like."

It's clear that we've still got a lot to learn about the intricacies of coffee. But we as a generation are, clearly, the best-equipped to take it further. "Although the industry has learned so much over the thousand-odd years it's been around, we still don't fully understand what makes the unique flavours that some people and places produce."

But that diversity is what keeps us hungry – or should that be thirsty? – for better, more specialised coffee. As Origin's Tarlo puts it, "it's what keeps folks like me living out of bags months out of the year to find those unique places, where the people and land make something really special."