When is a pint not necessarily a pint?....

....when it's beer!  Did you know that up to 5% of your pint can be froth, and still be arguably legal?  I say "arguably" because there is a measure of disagreement between Trading Standards and the British Beer and Pub Association.  The former say that a pint should be a pint (20 fl.oz.) of liquid, whereas the latter's guidelines say that the "head" is an integral part of the drink and can account for up to 5% of it.  Many pubs now use "line" glasses, which have a capacity of slightly more than a pint and where there is a line etched on the glass to indicate the pint level, and in general pubs using such glasses ensure that the liquid comes up to the line - but beware pubs that don't use such glasses - there's a very good chance that you are getting short measure!