In the first half of the 20th century, the use of adjuncts was very widespread. Usually in the form of flaked maize, though a few breweries, such as William Younger, used grits. So, it’s no shock to see that most of the Stouts contain some. 10-15% was typical, considerably less than the 5% here.
I think that it’s explained by the presence of another unmalted grain, roast barley. The two combined come to around 15%, about the typical adjunct percentage. Nowadays many associate roast barley with Stout but that wasn’t true in the UK. The vast majority of breweries used black malt instead. I can only recall two which used roast barley: Barclay Perkins and Guinness. The latter is doubtless the cause of the association.
Over 11% of the grist seems an awful lot of roast barley. Especially when there were another 15% of roasted grains in the grist. These beers must have been very roasty. Like drinking an ashtray.
I’m not sure if the oats were malted or flaked as the brewing records aren’t specific. The quantity is tiny, in any case so it doesn’t really matter. A token quantity so some could be sold as Oatmeal Stout. Oddly enough, it turns up in parti-gyles where I’m pretty sure none were going to be marketed as oatmeal. For example, IBS and RNS.
There’s a huge contrast with the two Export Stout, which contain no unmalted grains of any kind.
|Barclay Perkins Porter and Stout adjuncts before WW II|
|Year||Beer||roast barley||flaked maize||oats||total|
|Barclay Perkins brewing record held at the London Metropolitan Archives, document number ACC/2305/01/621.|