Thre is a special Jobling's article on Pyrex c1958 in the Glass-Study and it gives the impression that the Sales department were largely responsible. Also they( UK) take the credit for thinning down
Opalware to become domestic
TablewareImplication is that designs were used from US but adjusted at Jobling as needed for their market.
and this chappie:
Milner Gray, Esq., R.D.I., P.P.S.I.A. Director, Design Research Unit
However there was a PRODUCT DEVELOPMENT
E. Orange
and this one possibly...
 | GEORGE B. RITCHIE, Assistant Designer in his second year with Joblings. Mixed batch of likes: indoor gardening, painting, breeding Siamese cats, whisky, the theatre, the highlands. |
And then a PRODUCT DESIGN DEPARTMENT
J. D. Cochrane, Head of Dept
Miss Doreen Watson, secretary and general dogsbody (She could help)
all text images and data courtesy of the Glass-study.com