Most chose pale malt as base, Barclay Perkins being the exception in using mild malt. Though Whitbread did have some mild malt in the base mix. Barclay Perkins also stood out in throwing in some amber malt. An ingredient which was common in classier Stouts in the 19th century, but which had generally been dropped in the 20th.
Crystal malt was pretty popular. Which shouldn’t be a surprise, as Black Beers, along with Mild Ales, were the types of beers the malt had been designed for.
With regard to the principal colouring grain, there’s quite a bit of diversity. Only courage employed black malt, while Whitbread went for chocolate malt and Barclay Perkins and Truman both plumped for roast barley.
The malted oats in Courage Stout were presumably there because some was sold as Oatmeal Stout.
|Pre-WW II London Stout malts|
|Year||Brewer||Beer||pale malt||brown malt||black malt||amber malt||choc. Malt||crystal malt||mild malt||malted oats|
|Courage brewing record held at the London Metropolitan Archives, document number ACC/2305/08/263.|
|Barclay Perkins brewing record held at the London Metropolitan Archives, document number ACC/2305/01/621.|
|Whitbread brewing record held at the London Metropolitan Archives, document number LMA/4453/D/09/125.|
|Truman gyle book held at the London Metropolitan Archives, document number B/THB/C/114.|