I wonder whether Frank's comment on "another ewer ... suggested as Salvador Ysart" is about the one shown in the "Great Glass" site at:http://www.great-glass.co.uk/library/lib6a.htm
("Monart" section - item no. 7255)
I have handled that ewer and compared it to another of virtually identical form, which again now has my DNA imprint. In both of those cases, there was enough evidence for me to be 90% happy with a "Salvador Ysart" attribution.
But Ray's ewer is not really of the same detailed style, apart from having a "scroll top" handle and using flattened and stretched canes in the body. I do not recognise the canes but they could just as easily be imported from Murano as being "home produced".
I have no knowledge of the signature or of the particular seal on the base. But "Scilly" would make sense for an item produced in the Scilly Isles - possibly at around the same time as Jersey, Guernsey and Isle of Wight glass were first becoming popular, and which also sometimes had "seal" type signature logos.