2d per pint extra for high gravity beer

One of the unique features of tax rises in the first half of the 20th century is that they usually amounted to an increase in 1d per pint, retail.

At least that's what was usually claimed. But, as the tax was related to the gravity of the beer, the situation was, in reality, more complicated. The 1d was based on average strength beer. Obviously the increase would be greater for a beer of greater strength.

"TWOPENCE A PINT EXTRA ON HIGHER GRAVITY
As a result of the new Budget tax, higher gravity beers will be increased 2d. a pint, and not 1d. per pint as had been generally understood.

At a meeting of Derby and District Bottlers' Association yesterday the chairman said that it was very necessary to make it clear to the public that the new tax was on a gravity basis and that gravity beers are affected to a much greater degree than 1d. a pint.

The meeting fixed prices as under for Guinness Extra Stout, Bass Pale Ale, Worthington I.P.A., and Younger's No. 3 Scotch Ale delivered for home consumption as from Monday next: Bass, Worthington and Younger's, 12s. 6d. per doz. pints, 6s. 6d. per doz. half pints, 5s. per doz. nips. Guinness E.S., 11s. 4d., 6s. 2d., and 4s. 10d. respectively.

Gravity of beer depends on the amount of alcohol, hops, malt, and barley contained. A higher gravity beer is essentially a brewed beer with a higher percentage of these ingredients than the cheaper and chemically treated kind. In most cases brewers use "X's" to indicate the strength of their ales and stouts, and those that will go up by only 1d. pint are, generally speaking, those denoted by one X." "
Derby Daily Telegraph - Saturday 27 April 1940, page 3.

I understand the basic principle. But were the beers mentioned really so strong that the tax increase was 2d per pint? Why don't we take a look?

The increase in April 1940 was from 104 shillings per standard barrel to 135 shillings. A standard barrel being 36 Imperial gallons at 1055º. Luckily, I know the gravity of all four beers mentioned. They were all well above average strength, but nothing like double as strong.

Looking at the table below, you'll see that the increase in tax for an average strength beer was about 1d per pint. For the four higher-gravity beers, it's more like 1.25d.

Effect of April 1940 tax increase
Beer	Tax in shillings	OG	tax per barrel (shillings)	tax per pint (d.)
Average OG beer	104	1041	77.53	3.23
Average OG beer	135	1041	100.64	4.19
Bass Pale Ale	104	1056	105.89	4.41
Bass Pale Ale	135	1056	137.45	5.73
Guinness Extra Stout	104	1054	102.11	4.25
Guinness Extra Stout	135	1054	132.55	5.52
Worthington IPA	104	1055	104.00	4.33
Worthington IPA	135	1055	135.00	5.63
Younger's No. 3	104	1052	98.33	4.10
Younger's No. 3	135	1052	127.64	5.32
Sources:
1955 Brewers' Almanack, pages 50 & 80.
Truman Gravity Book held at the London Metropolitan Archives, document number B/THB/C/252.
Whitbread Gravity book held at the London Metropolitan Archives, document number LMA/4453/D/02/001.
William Younger brewing record held at the Scottish Brewing Archive, document number WY/6/1/2/76.

Looks like the bottlers were taking the piss.

Given that the four beers were of very similar gravities, I wonder why Guinness Extra Stout was cheaper? What do the beers have in common? They were all nationally available.