Sadfield
Landlord.
Well. if were going to link to Barclay Perkins, I'll counter with the following passage. It appears odd that breweries would take the retrograde step to Single strains knowing that mixed strains produce better beers in the 1940s. But there we are.I know Adnams use a dual strain and I believe Harveys do and their yeast came originally from John Smiths. The man at Green King told me they use several strains within the brewery because of the brands they have taken over so the Old Speckled Hen is brewed with the original Morland yeast.
This may be of interest Yeast map the bottom comment from the beer writer Martin Cornell about the GK yeast.
As for my local yeast Peter the head brewer at Crouch Vale told me they do have their yeast analyzed each year and it remains constant whereas the yeast they gave to Wibblers has varied to an extent they registered it as their own strain but again it remains constant for them. According to this An updated brewing yeast family tree | Suregork Loves Beer the original Ridley's stain is closely related to Timothy Taylor's.
"Pure Yeast Cultures
In "Brewing Science and Practice: Volume II Brewing Processes" (H. Lloyd Hind, London, 1940, pages 800-802) there's another interesting passage about Hansens work with single-cell yeast strains. It discusses experiments at the Worthington brewery in Burton in the 1880's brewing beer with pure strains. The conclusion was that pure strains did not produce better than mixed strains and ib fact had some disadvanatges during secondary fermentation, such as conditioning more slowly in the cask and producing beers which did not age well. It was not recommened for use in beers that were to be kept more than 6 weeks after racking. It says that at the time (1940) only a handful of British brewers used pure strains."
Yeast circa 1900