In The Gazette, the specification of all coins are laid out clearly. From the precise and legal jargon, I would say it was clear that these specifications must be met, except for a minute variation in weight/dimension as set.
But I wondeering if there is a requirement for coins to display their denomination? I assume so, or there would have been no need to reissue a specification for the ciruclating coin.
It would seem that at LEAST date, deonomination and effigy are required. And there may/must be guidelines on the useage of the writing too.
I would love to find out where these requirements are laid out. I cannot believe that they are just rough conventions that are adhered to.
My overall point is that this coin seems to be a case of Specification Error, in which the specification omitted the deonomination in error?