This isn't a subject I'm likely to start foaming at the mouth about! Surely the "square" ones have rounded edges so are not even square.
Didn't Ind Coope Burton Ale do some large oval ones or is that a memory management violation?
Oval with "ears" at the corners, two sets of them were produced around 1980.
Drink drink, whoever you may be,
we are the drunk and disorderly,
and we’ll drink more beer wherever we may be,
and we’ll meet you all in a pub said he.