Hi,
If you are based close to Sunderland, there must be research materials availble in the local archives, and at Ashburne House, Ryhope Road, Sunderland, which houses the University's glass department. You may also find that there have been exhibitions on both the glass and the manufacturers, held at the Reg Vardy Gallery, so ask there or the reference department of the local library.
Regards,
Le Casson