Wow, this certainly IS something - it's Monart. Quite possibly a miniature. If it is, it is of fairly serious value.
Would a moderator be so kind as to shift this thread to the British and Irish glass forum, so the folk who really know about it can comment?
welcome to the board, mbdouglas. Have a search/ look around that forum for Monart + miniatures - there has been recent discussion about these!
I've just got hold of a ruler, (tape measures have all gone into hiding - I know I had one yesterday - it was snaking all over the sitting room floor. I knew tidying it up was a mistake.)
8cm is marginally over 3" - you may need to check the "Scotlandsglass" website for the shape number - that will give you the sizes of vases made in this shape, and if this size isn't one of the "normal" range, then it's a miniature - rather a scarce a highly desirable beast!