If we went metric, half a litre's about 7/8 of a pint...
Bollocks, though: a pint s just right. Measures to encourage reduced consumption ("nudges") never work in the UK: I recall an article I read some years ago pointing out that Britons (well, mainly young British men, I suppose) have been drinking specifically in order to get drunk since before the Norman invasion, so we're unlikely to stop now.