Many thanks, Paul. Queries totally resolved.
RD 297041 is definitely Sowerby pattern number 1129, and this covers the open sugar, the covered sugar, and the creamer.
Now that I know exactly what RD 297042, the sweetmeat, is supposed to look like, I can conform that it appears as pattern number 1031 (along with other sweetmeats or jellies) at the bottom of page 44 of pattern book X! (1885).
I have yet to see a photo or actual example of pattern 1031 though.
As you say, Paul, the registration representations are works of art in their own right - if only they were available online....