According to the Blue Book Rd. 681652 was registered by Stuart on 12th March 1921, and on the same day they were also allocated 681649/50/51 - so a total of four Nos. on the same date.
What the other Nos. referred to I don't presently know, but can look in the Kew records when I next visit,
unless of course someone else already knows to what the others refer.
I'd say it's unlikely that any of these four Nos. refer to etched or engraved decoration - it's usually shapes only that were being registered.
The early 1920's were a time of prolific Rd. activity for Stuart, no doubt a lot of which were for items in the Stratford Rings service - some of which continued well into the 1970's it seems. Unfortunately, there really isn't any paperwork easily available showing the factory's designs - from memory believe there were limited editions (expensive) of some volumes with information collected by Mr. Gulliver, but now not sure.
I've looked in the Miller's/McConnell book, where he devotes several pages to Stuart, but don't see anything in the way of decoration showing cock fighting etc. - neither does there appear to be anything in CH's second book - so no clue as to when this decoration was produced. Certainly it mustn't be assumed - as is often wrongly the case - that decoration (or manufacture come to that) is related to the date of Registration.