hello Keith - can you give us a pic of the underside of the foot please, it might help with placing a date more accurately.
I don't think it looks like a Stuart piece, in fact it may well not even be from the U.K. - but have a look at Hajdamach's 'C20 Glass' page 116 re the Hugo Masey work that he did for Webb Corbett - the piece on the extreme right. About as near as I can see.
Does it ring, or is it a clunk piece?