It's the Arms of the City of London:
... and on further investigation it seems that ever since this little metal thing was introduced into our system of exchange, the Royal Arms have been omitted (except for the 1988 design) in favour of a cycle of images from the regions.
Doubtless we'll be told not to take it too seriously, but it seems to me that the 1.5 billion pound coins are being used as yet another method to condition us to accept the "inevitable" breakup of the Union.
Another subliminal point, maintains the wife of a friend, is that the change from a banknote to a small coin was to help us not to expect so much for our money.
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