I think several companies have made 'thistle' glasses, and probably over quite a long period of time. I have a couple of 'thistle decanters, one of which is an early version of the Edinburgh one, with the thistles engraved round the base (but sadly with a replacement stopper :cry: ) and another with a longer neck and no engraving, which may or may not be Edinburgh. I also have a small glass, no thistle engraving, but with a knopped stem. I don't think this is Edinburgh, although it could be, as they did vary the design over time, and they did do plain as well as etched versions.
I like yours, with the cutting down the stem, and star-cut foot

Sorry I can't say who made it or when. You could try searching on 'Replacements'.