Brettanomyces, stock ale and the origins of porter - Ferment Magazine article

My second article in Ferment magazine is probably one of the geekiest pieces I've written about beer, ever.

It's all about the origins of porter in London and the importance of aged stock ale in it's flavour profile - particularly the effect of Brettanomyces. You can read the full piece, along with lots of other great stuff, in the online version of Ferment Magazine here: or alternatively I've reproduced it below if your prefer.



From London’s market porters to Belgium’s trappist monks – how British wild yeast changed the beer world forever

By Neil Walker of and member of the British Guild of Beer Writers.

After very nearly dying out all together in the 1970s, porter has seen something of a resurgence in popularity in recent years, thanks in no small part to the craft beer revolution that started in America, then quickly spread back across the pond to the birth place of the beer - Britain.

With a history that stretches back to the 1700s, and once the most popular beer style in England, porter was traditionally a mix of ‘stock’ or aged brown ale and fresh, unaged ‘mild’ ale, that was combined in quantities specified by the customer when ordering at the bar. Whilst some preferred more of the younger, fresher beer, and others preferred more of the complex aged beer, what was consistent was that ageing was a key part of the flavour profile of porter.

Wild yeasts from the wood, oxidation, and hundreds of other microbes and bacteria which went to work on the beer while it matured meant that what came out at the end was very different to what went into the barrels at the beginning. Dankly fruity, funky, almost port-like in its intensity, aged beer can be as complex as any fine wine and have all the depth of a well matured whisky.

Yet don’t be tricked into thinking that this multifaceted, partly aged, concoction of a brew was the preserve of the upper-classes – porter was very much the everyman drink of its day. In fact the name porter came from its popularity with London’s street and river porters, the working class men who did everything from unloading coal from river barges to lugging sacks of malt to the buildings brewing the very beer they drank so much of.

Whilst you probably wouldn’t get away with calling it a foodstuff nowadays, this thick, hearty, nourishing beer was heavy with carbohydrates and very much used by the London porters as fuel for their work, accounting for up to 2,000 calories worth of their daily food intake.

But despite its popularity nobody actually knew what was happening to that beer while it matured, or what exactly gave it the distinctive flavour described at the time as ‘racy’ yet ‘mellow’, but which modern drinkers might view as ‘funky’ or ‘complex’, and ‘smooth’ or ‘balanced’.

In fact, it wasn’t until 1904 that the specific wild yeast which was giving British porters their distinctive aged flavour was isolated and named – and it happened not in London, but in Copenhagen, at the original Carlsberg brewery in Denmark, where N. Hjelte Claussen was investigating the causes of spoilage in British ales.

After its discovery the wild yeast in question was named Brettanomyces, which comes from the latin for ‘British Fungus’ - an homage to its origins in the aged porters and stock ales made famous by Britain.

Nowadays the beers which best display the effects of Brettanomyces, or brett as it is often shortened to, are Belgian beers such as Orval, which when drank fresh is spritzy and hoppy but which develops a distinctive farmyard funk after a few years in the bottle with brett as a bedfellow.

Whilst modern British porters tend to leave the brewery as complete beers rather than being mixed to order by barmen, there are still ways in which you can get close to experiencing what traditional porters of the 18th and 19th century could have tasted like.

One beer which has all the funk and just a hint of the sourness of those original porters, but turns it up to eleven, is Harvey’s Imperial Extra Double Stout (which is a style that is in many ways the grandchild of porter, but that is another story entirely).

A well-aged bottle I drank recently was an explosion of sour berry fruit on the nose, with more than a little of that distinctively funky, almost dank smell of Brett. The flavour was a constantly evolving mix of funky sourness, rich fruity espresso, dusty white pepper, tart cranberries, dark chocolate and heaps of sticky berry fruit.

Thanks to heavy hopping - as was typical of porters back-in-the-day - the finish has a spicy bitterness that goes on and on, and a complexity which can only be achieved through careful ageing.

Other wonderful examples of porters brewed to traditional recipes, though sadly without the addition of that now famous British yeast, are Elland’s 1872 Porter, The Kernel’s Export India Porter and Sam Smith’s Taddy Porter – all very much well-worth a try.

Just don’t blame me if your boss refuses to let you enjoy one on your lunch break, despite the historical significance.



  1. Claussen wasn't investigating spoilage in British beer, he was investigating why pure yeast cultures originating from a single Saccharomyces cell didn't work when making British beers. Having isolated Brettanomyces he said it gave "that peculiar and remarkably fine flavour" found in English stock ales. Ron Pattinson has put a scan of the paper online:

    Harvey's actually have another 'wild' yeast that gives their Imperial Russian Stout it's distinctive flavour: Debaromyces hansenii:

    However, the Old Dairy Brewery have been making an Imperial Russian Stout with Brettanomyces for a few years. It was on draught at the recent White Horse's Old Ale Festival, and very good it was too.

    I suppose I'd better also mention that technically speaking Brettanomcyes has now been renamed as Dekkera.

    And yes, it has been a bit of an obsession of mine!

  2. Porter was a mix of aged Brown Beer and Mild Brown Beer, there was no Ale in it at all. It might seem like nit-picking, but it was an important distinction in the 18th century.

  3. Hi Ron,

    thanks for the input! It was an article I expected to be open to nit-picking - the best I could hope for was no glaring mistakes. Thanks for the tip and duly noted for future.

    Always hard to get the balance between making something readable to a relative novice and upholding factual accuracy.

  4. I find it a nightmare to write about the 18th century. Without using the term "Malt Liquor" it's hard to write anything that's accurate for the terminolgy of the day.

  5. Sorry I've come a little late to this. The rather elusive Pope's Yard sent this ti Carnivale Brettaonomyces in Amsterdam last June:

    It appeared to be an attempt to recreate a staled porter from the 18th (early 19th) Century. Not sure how authentic it might have been (Ron may have a take on this) but it was certainly interesting.

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