I think mine must be pretty early - the hot glass facitities at the RCA only became into being in late '66. I'm not a good photographer, and it's a difficult piece to show properly - there are 4 sets of "double-bubbles" around it, formed into yin-yang shapes, with silver salts which give rise to the bluey-yellowy irridescent appearance in reflected light, while turning the amethyst to amber when the light comes through it.
There are quite a few unintentional bubbles - it's a wonderful combination of a sophisticated idea appearing through a struggle to master the metal.
According to Pauline's statement in the booklet which accompanied "The Glasshouse and it's Tree" ( page 10) exhibition last year, she set up a studio in Gloucestershire in 1975, while continuing to show at the Glasshouse, and;-
"Three years later, Harry and I established Cowdy Glass Workshop for which I designed functional work, selected for the Design Centre, and then founded Cowdy Gallery where I have curated numerous glass exhibitions over the years."
According to Graham McLaren, "Studio Glass 1960-2000", p.14, her first studio in 1975 was in Ravenshill. Perhaps that's your RH.
This is a very nice little booklet, published by Shire, loads of lovely pictures.
ISBN 0 7478 0527 X. It cost Â£4.99. www.shirebooks.co.uk