Joan O'Leary was a student at Whanganui under Tony Kuepfer - one of the first group of graduates in Design from Whanganui. In 1989 she worked at Inglewood with the Simpsons and Andrew Williams, then from 1992 Joan worked with Mandy Angus in New Plymouth. In 1995 she worked at UCOL Whanganui as technical assistant for David Traub. She subsequently married; her rural location forced her to give up glassblowing.
This piece is typical of the work produced at Glassplant, Inglewood by the Simpsons and Andrew Williams. I suggest the date is most likely to be 1989 or 1990, rather than a decade later as you suggest.