I think Allencrisp must have been drinking in some cheap places: I started drinking in 1973 (in Brighton) and bitter was about 15 or 16p and lager was about a penny dearer - I don't think that the price would have gone up 5p in a year.
Surely it depended where you drank: in those days there was a different price in the saloon and public bars and pubs on the seafront tended to be more expensive. I also remember being shocked when I went to uni in Yorkshire and found that bitter was about 4p cheaper than it was at home.