I've just noticed this. According to Ron Pattinson (but what would he know, eh ...) "beer" (which would cover "porter") was sold in 36 gallon barrels whereas "ale" was sold in 32 gallon barrels, which makes all ale more expensive! Which is what I said! Err ... I said ... damn!... Mild wasn't cheaper than Porter in the Victorian period. The cheapest - X Ale - was the same price, 36 shillings for 36 imperial gallons. XX, XXX and XXXX Ale were more expensive.