This definition is mostly based on 1950 to 1975. Immediately after the war, no beers of this type were brewed due to government restrictions of gravity. By this time pre-war PAs at places like Fullers and Whitbread were a shadow of their former selves, with gravities in the low 1030ºs. They'd become Ordinary Bitters.
A new breed of Best Bitters started emerging around 1949 when brewers started to have the freedom to introduce stronger beers. I haven't found a single example of an old PA having its strength bumped up. These were all newly-introduced beers. A classic example is Fullers London Pride, but most of the then still numerous London brewers had an example.
The grist was quite similar to pre-war, with a couple of exceptions. At the start of this time slice flaked barley was the usual adjunct, simply because that's what the government insisted on. Once they had the choice, brewers universally switched back to maize. The use of crystal malt was becoming more common, but only in relatively small quantities. It was still not universally present in this class of beer.
No.1 and No. 2 invert remained the favourite types of sugar. Fullers continued to use a little glucose in their Pale Ales. Some beers also included a little caramel for colour adjustment.
Hops from all over the world continued to be imported, but in much smaller quantities than before the war. With the UK just about self-sufficient in hops there was far less need for foreign examples.The ones which were imported tended to be higher-quality varieties such as Styrian Goldings ,Saaz and Hallertau. Most beers contained 100% English hops.
|Postwar London PA (Best Bitter)|
|SRM||5 - 8|
|flaked barley or maize||10-15%|