One final post for Mild month. Some writers maintain that, rather than disappearing, Porter was transformed into Dark Mild. Is this true? Is there any evidence to support the theory?
I'll lay my cards on the table at the start. The theory is bollocks. OK, I guess you'll need a little more than just that simple assertion to convince you. Here goes.
What did "mild" mean?
In the 19th century "mild" meant young or unaged. It was used in subtly different ways and I believe this is responsible for some of the confusion over the relationship between Mild Ale and Porter.
In 19th century texts "mild" is used in two different senses. The first is to refer to a specific type of beer, Mild Ale. The second is to just young beer in general. So if you read a sentence like "Most of the new trade is for mild." it doesn't mean specifically Mild Ale was the greater part of new trade, but young beer. It's an important distinction.
Towards the middle of the 19th century there was a switch in public taste away from Entire (aged Porter) to Ale and mild. Not necessarily to Mild Ale. Increasingly, Porter was sold mild, that is unaged. Simultaneously Ale was becoming more popular. Specifically X-Ales. These were usually sold young as Mild Ales, though Old Ale existed, too.
Did Porter and Mild merge?
I can say this with certainty: not in the London brewers' logs I've looked at.
Let's look at Barclay Perkins. For a couple of decades at the beginning of the 1800's they only brewed Porter and Stout. No Ales of any description. Around 1850-ish they reintroduced Ales and built a new brewhouse to produce them. The brewery was divided into "Porter side" and "Ale side". They operated independently of each other and had separate brewing logs. It's hard to imagine a greater distinction than that between their Mild Ale and Porter.
For reasons I've still not worked out, Barclay Perkin's Porter was always called TT within the brewery. Their Mild Ales had the inspiring names of X, XX and XXX. My last sighting of TT in their logs was in 1937, when it was a poor shadow of it's former self with an on OG of just 1027. In that same year, they were brewing two Mild Ales, X and XX at 1035 and 1043 respectively. I can see no merging there.
What about the grists? In the 19th century the Barclay Perkins Milds were 100% pale malt. Their Porter was pale malt, brown malt and black malt. Not much similarity there. As their X Ale grew darker it started to include amber malt, dark sugar and caramel. But no brown malt (with the exception of during WW I), the defining element of London Porter. These are the malts used in the late 1930's:
Porter: Oats, amber malt, brown malt, crystal malt, roast barley, mild malt.
X: Amber malt, crystal malt, mild malt, pale malt.
Dark Mild and Porter existed alongside each other for decades and were brewed from very different grists. I think that torpedoes the Porter becomes Dark Mild theory and send it to a watery grave. (Which is coincidentally what Porter had, a watery end.)
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