very nice piece ............ I wonder why put Roe Deer when the engraving shows a stag?? Are we sure this is an S?
The initials aren't particularly legible, although the M is probably not open to interpretation, but assuming the initials on your piece are identical to the one in your link, do you think there's any possibility the first letter might be I.
My reason for this suggestion is that one of the engravers/sandblasters listed in Mark Hill's book is an Irene McCoughie. I'm probably wrong - but just a thought.
Could be wrong, but I think the Board has an issue with showing material from other sources without permission - is there some reason you're not able to attach pix of your vase?
Ref. 'Caithness Glass - Loch, Heather & Peat' - Mark Hill - 2011.