There is an image of your exact piece on p.59 of the book; Caithness Glass; Loch, Heather and Peat.
The text under it reads;
"Five 1970s-80s Specimen Vases, no.OG18, from the Oban range, designed by Charles Orr and Peter Fuin in 1969...
The form was designed by Peter Fuin and was based on O'Broin's teardrop specimen vase. Each side was flatttened and rolled slightly on the marver table, the form was then elongated by swinging, and the base was flattened using a pad on the floor. As such, each example is unique in precise form and size. A twist could be added..."