Will there be a proclamation issued for this coin? I have not seen one so far.
Same applies to the second Gruffalo issue.
Can some coins be issued by RM without a proclamation?
The issuance of the second Gruffalo and the Wallace and Gromit 50p coins has indeed not yet been gazetted. All UK coins have to be gazetted and as far as I know this has always happened before the coin is being issued. Although there is as far as I know no requirement to do this beforehand, in light of legal certainty etc. it is no more than normal that it happens before the coins are being issued.
The 2019-dated Peter Rabbit 50 pence coin was issued without Gazette proclamation, something that I have yet to discuss with their lawyer.
It is customary that coins that vary slightly from a coin that has been Gazetted (for example editions with a special mark or micro lettering) do not require a separate Gazette publication. The science edition of the 2019-dated Britannia 50p coin is an example of this.
As for error coins, if at least a part of the coins does not have the error, the Mint does not have to publish a seperate Gazette publication for the error coins. If all of the coins have the error they have to alter the existing proclamation.
Her Majesty does not formally approve coins in January, August and September which may explain why it has not yet happened.