I think it is, in part, down to being the first country in the world to have an industrial revolution - large mass of the population moving from countryside to industrial centres for work in factories (a new form of serfdom
).
Oh fuck, how are we going to feed them? I know, we can put loads of additives in bread (powdered chalk was used to bulk out flour at one stage).
The plebs keep on dying/fainting at their machines; well we can give them a lunch break (unpaid) so that they get back to work quicker.
Two world wars, rationing - my mum was very angry about rationing, I think that UK still had rationing in 1954. She lived in Germany (as my father was in the British army) and was disgusted that the British were being treated less well than the Germans (rationing ended there in 1950)
By the sixties, we embraced the "brave new world" of space, Dan Dare, nutrient pills etc. No need for "proper beer", feed cows ground up animal remains along with doses of antibiotics for great growth rates/productivity, churning out bread on a conveyor belt (having been steamed, not baked), had a certain attraction - not least higher productivity/profits.
Simplistic interpretation, but it works for me