On Tue, 26 Jun 2018 10:40:41 +0100, "NY" wrote:

snip

I had never realised that the flats on a 20p or 50p coin were arranged so
the distance between one edge and the other, for any line that goes through
the centre, was always the same, irrespective of which part of the flat or
point the line happened to go through and even though the middle of that
line may not always coincide with the centre of the coin.

I think that was so they would be acceptable in slot machines.

Cheers, T i m