Looking at some of the remarkable design by Helena Matos and Pedro Alvarez for the 1972 Hand made factory glass exhibition, I wondered about Fabrica Escola Irmãos Stephens as Stephens seemed an odd name for a Portugese glassworks. Turns out that he was an English industrialist, William Stephens, who in 1769 got the charter to restore/restart the Royal Glassworks and ended up founding Portugal's glass industry. He died c1830 but his family obviously continued and the glassworks was by the 20th century the National Glassworks. (Various names in between and later). But in general very little information about this. There is, or will be, a national glass museum in original buildings. Stephens Palace being a separate sight in itself.
If anyone can add anything, would like to hear.