I have discovered a vase that is enamelled and signed Webb Corbett that also uses this acid cameo background.
No idea how big it is though as despite it being thousands to buy, the seller hasn't listed the size
Anyway, it appears they used this background for at least one vase.
I have also found it used on another English makers piece dating to a similar period.
There 'might' be a connection between that other English maker and Webb Corbett. I have evidence of a possible connection.
The handles of this little vase remind me of something the other maker has made.
Long shot - probably not either the other English maker nor Webb Corbett given the style but I've just added the information just in case.