Problem is they keep changing the rules about how big a modicum is.

It's bad enough with US pints being a different size from UK pints, and never mind how big 'cups' are.
And the BBC insisting on measuring distances in kilometres when all UK road signs and speeds are measured in miles.
And EVERY time they start telling you how many 'units' you are allowed, they try to explain how to work out how big a unit is (and while you are trying to work out how many units you drink you miss the rest of the programme or news item).

I've decided that however much I drink or eat, that's how big a modicum is, and if I happen to drink more it just means the modicum got bigger. If 'they' can change the rules then so can I.