Some beers smell so good that sipping them too soon would be a sin. Instead, when I find one like this, I sit there quietly huffing it for a while, taking in its heady aroma and enjoying its complexity. I know this a good sign whenever it happens and won’t let myself be rushed. And when I finally get around to taking that first sip, beers like this never fail to amaze me.

This time, the beer in my glass was a new release from Mills Brewing. It was a bright hazy orange with a thick collar of dense white foam. And it was blessed with one of those head-turning scents you can smell halfway across the room as it’s being poured. Served in a wineglass, in a caravan, in the rain, its superb colour and condition banished any concern for the outside world for a moment. It seemed to glow; to radiate goodness. Never mind we had a cab booked and due any minute to scoop us up and take us out to Bristol. I took my first sniff of the aroma and knew this beer demanded time and attention.

Let me backtrack a minute and cover the basics. The caravan, for a start. It belongs to Gen and Jonny Mills, the husband-and-wife team behind Mills. It sits in the yard outside their brewhouse in a little Gloucestershire town called Berkeley. The brewhouse is an old barn next to a river on the edge of the town. Before the pair took it on it had lain abandoned for a handful of years. Jonny reckons maybe five.

A short walk further down the road takes you to The Sally, a pub with a long string of awards to its name where Jonny also brews Tiley’s beers. Until recently Gen and Jonny were living above the pub too. But now they’re in the caravan, living on site, pouring every bit of time and money into the brewery they have built up together.

Living like this can’t be easy. The caravan is not large. I’m left wondering how they manage the everyday domestic tasks most of us take for granted. It has to be a pain at times, but the pair clearly have great stores of dedication to the life they’ve chosen. Nothing in it could be described as the easy way.

Gen and Jonny set up Mills to produce beer with “minimal modern intervention”, relying instead on spontaneous fermentation from wild yeasts. Jonny produces the wort for Mills at The Sally. He uses same the turbid mash method that traditional lambic producers employ in Belgium to brew their beers. It is more challenging and more time consuming than most brewing methods, but it produces a wort more suited to the slow fermentation characteristic to wild yeasts.

They transfer the wort from The Sally to the brewery by pumping it into a tank in his van, then pumping it out into their coolship. These are normally wide and low-sided troughs, open to the air, but the one at Mills looks suspiciously like an old mash tun. As the wort cools, it is colonised by microorganisms from the surrounding environment. It is these microorganisms, rather than the usual brewer’s yeast, which will ferment the wort and turn it into beer.

The fermenting and ageing takes place in wooden barrels. Mills use as little stainless steel as possible, preferring to choose wood where they can. There are white and red wine barrels lining the walls, and some bourbon barrels too. Each one carries the brew number and barrel’s previous contents written in chalk. The younger ones have orange airlocks to vent the carbon dioxide released during the active fermentation going on within. The older ones, full of quietly sleeping beer, breathe gently with passage of the days and the weather as it warms and cools the barn. The beer seeps into and out of the wood, over and over again, taking on some of its character each time.

“We keep all our barrels and maturing bottles at ambient temperature as we hope to encourage seasonality and the influence of nature into every beer we produce. The local environment and weather are crucial in helping us to produce an ever changing and hopefully endlessly interesting series of releases and vintages.”

Making the wort and filling the barrels takes some knowhow, but the real skill comes into play years later when the time comes to blend and bottle what will become the finished beer. Blending is a unique skill that requires a finely attuned palate. The usual practice is to blend two beers, one young and one old. You need an intimate knowledge of the beers produced in each barrel, as each one will be different from the next in some way. The idea is to balance out the various characteristics to arrive at a blend which showcases the best of both beers.

Once blended the beer undergoes a further fermentation in its bottle to carbonate and condition it. There are great cages in the brewery filled with bottles, all neatly stacked in interlocking rows. You need to anticipate how the beer will continue to develop as it matures. This too is affected by the climate.

‘Today’ – the beer we drank in the caravan that gave me that moment to pause – was a blend of two beers, taken from three barrels, that were brewed back in the winter of 2016. It was bottled in April and we were tasting it for the first time in August, not long after a long and intense heatwave that must have spurred fermentation across the brewery to new heights of activity. It is the first of Mills Brewing’s spontaneously fermented beers to be released, and as such represents the culmination of years of planning and work.

The beer is bright and clean, sharp and complex. It sits comfortably within the realm of spontaneously fermented beers that includes the traditional lambics of Pajottenland, but is its own thing, distinct and unique. Delicate fruit notes dance around the sour bite. It possesses a quiet elegance. The labels are beautiful but not showy. The beer has room to speak for itself, and it speaks volumes.

Together Gen and Jonny have created something special, and entirely on their own terms. Everything they do at Mills speaks of dedication and passion. Gen hand labels the bottles, for instance, dusting and polishing each one first. (The labels feature artwork by Gen’s father, Martin Kaye, some of which also hangs on the brewery walls.) They are two of the nicest, most welcoming people you could hope to meet, making some of the best beer you’ll ever be lucky enough to drink. I was extremely fortunate to be invited on this trip by Dan at Kill The Cat. Look out for Mills beers on his shelves in the near future.