London Baby

London Fog

This blog is going to focus on the quite specific subject of the London Fog Ale Yeast strain, which has become increasingly popular amongst craft brewers. We’ll look at where it got its name from and for what kind of beer it is used, as well as which of our beers it has featured in recently.


So first of all, what does London Fog actually refer to? It is quite a general term in that it describes how the British capital suffered from terrible air pollution during the 19th and 20th century. In 1952, there was a particularly bad case, known as the ‘Great Smog of London’ during which many people died or suffered from severe respiratory problems. This build up from air pollution creates a thick yellowish fog, which has also been referred to as ‘pea soup fog’. The general name of this phenomenon, London Fog,  has since been used for a London tailor’s brand, bars and pubs and more recently, our yeast strain…careful what you call a bag of yeast in London though, in cockney slang, it refers to a priest or worse, even a beast!

The science behind it

Its name and background story should give you some kind of a clue as to what the yeast strain will do to our beer. Yeast is an essential ingredient in beer, as it eats up our sugars in our wort to create both alcohol and CO2. We can use a variety of yeast strains to brew either ales or lagers, and they can add all kinds of distinctive characteristics depending on the beer style we’re aiming to brew. Yeast also contributes to flavour in our beer, and when compared to other yeast strains, our London Fog Ale Yeast strain allows for more residual sweetness and helps retain some of the fruitier elements from our hops. The result? A lovely juicy, fruity and full flavoured beer! As for its appearance, as it stays in solution, well it gives the beer a lovely haziness or ( or should we say fogginess?) and as such it shouldn’t come as a surprise that the London Fog strain is ideal for brewing a New England IPA. Whilst it is still a relatively new yeast strain, it has proved to not only be a hit here at Uiltje but amongst craft brewers generally.

From London to Haarlem

We have recently used the London Fog Ale yeast strain in our My Lifespan Is, a NEIPA collaboration beer with our friends from de Moersleutel and Lehe. A NEIPA that has been packed full of hops – including two of our favourites, Mosaic and Citra, the label of the beer is a giveaway in terms of the need to drink it as fresh as possible – ideally within 3 months! Those of you who were lucky enough to have gotten your hands on this beer will hopefully also have noted its lovely haziness. We have also used the London Fog Ale yeast strain to brew one of our latest Fresh & Fast beers, the Pacifica Sonata, a New Zealand hop based NEIPA, which is also best enjoyed as quickly as possible. Whilst My lifespan Is and Pacifica Sonata were one offs, neither will be returning anytime soon, however keep an eye on our upcoming NEIPA’s that will also be brewed with this yeast strain. Make sure to follow us on social media to keep updated, or better yet check out our webshop!