There should be an image of "two pontil irons with a blob of glass at each end" as your pontil mark stamp.
Dartington Studio was a very short-lived enterprise - they were handmaking some very adventurous pieces - loosely based as tributes to other, more classical designs and using the original techniques and materials. For example, when they did their ruby twisted bits, they did actually use gold to colour the glass. However, it proved too costly to survive.
I believe the plate you have is loosely based on Monart and WMF - with the use of the "Crizzle" technique(That's what it's called when done at Mdina, although I have been told the official generic name is "primavera"). This involves dunking a hot gather into cold water at some point to crack the surface. It is then further blown and cased.
Pieces don't turn up to often, they're mostly pretty fabulous.
(I can't stand the ruby twisted bits - a bit pink-pretty-frilly for me)
I believe they have another, more current, range of "Studio-style" pieces, under the name of Innovate.