Quote from 2008 annual report Portmerion group plc, page 7
Principal activities
The Group markets ceramic tableware, cookware and giftware, glassware, candles, placemats, coasters and other associated products, and manufactures ceramics. There have been no changes in activities during the year.
The report also says that in 2008 58% of the ceramics was made in Stoke on Trent and 42% was outsourced to China
As Ivo says Portmerion does not make glass