The Ale log for the years 1932-1936 is a good example. Glued to the inside front cover are two price lists. One from before the lowering of beer duty in April 1933, the other after. They are an absolute goldmine of information, especially as they relate directly to the beers in the logs.
Take a look for yourself:

I've combined the information in the price list with details from the logs to come up with this table:

You'll notice how slim the publican's profit was - just 25% to 30%. That's much less than today.
Something that is only apparent by looking at both the price list and the logs together is the nature of Whitbread's Light Ale. Just looking at the price list I would have assumed it was a pale beer. Having seen the log, I know that not only was it dark but that it was party-gyled with the X. It's not what is usually known at Light Ale (bottled ordinary Bitter), but is in fact a low-gravity bottled Mild. Only looking at the log, I would have assumed it was a draught beer.
It has been argued that Pale Ale and Bitter are not synonyms but two distinct styles. This price list shows that, for Whitbread at least, they were exactly the same thing. The name Pale Ale was used within the brewery, Bitter in the pub.
As a special bonus, I've produced a detailed breakdown of the ingredients and brewing process (as much as I can understand it). It may be of interest to homebrewers. Sorry about the lack of final gravities - they aren't in the log. The ones quoted in the table above come from 1940 (courtesy of the Whitbread gravity book). If there's any interest, I may do some more. It takes lots of my valuable time (I could be watching Hollyoaks). Tell me if I should continue. Oh yes, you may need to scale down the quantities a bit.
