and if you don't want to know the answer, look away now please.
Described in the Board of Trade Register (at TNA) as a 'Salt Sprinkler (cruet like)' - CLASS IV as I thought, and there obviously was a metal frame of sorts although this not shown or described in sufficient detail to really get an idea of its appearance. The Registrant appears to have traded as silversmiths, with their address as Holborn in London. CLASS IV was specifically for pottery and ceramics - quite why some of these things ended up there is a mystery, unless the idea was to hide the design from prying eyes.
The similarity of the design of John's - compared to the larger Fieldings pair - is striking (albeit without the indent for the metal frame on Fieldings) - and all three are very unlike Peter's bitters bottle. Are we tempted to think Fieldings may have mis-described theirs, or is that being unkind.