Thanks for taking the time to upload the images Sue, interesting.
It's always a little difficult comparing colours online, especially when they are similar. Hard to say, but If committed, I think my piece has a slightly more aqua/greeny hue to the glass. Although, the purple does look similar, having said that the purple in the Whitefriars streaky vase (I use to own) in the attached photos, does also look pretty similar again.
Thanks for the info on Caithness/Dartington, I'll think I'll hold off contacting them for the time being, as you say, probably unlikely to get much feedback in terms of slightly older pieces.