I also meant to query this possibly misleading comment:
Cast plate-glass had been invented in France in the seventeenth century. In Britain a factory producing cast plate-glass opened at Ravenhead, near St Helens, in 1773, but the heavy excise duty on glass inhibited the growth of the industry, and by the 1830s there were only two factories, both in the north, at Ravenhead and Newcastle upon Tyne. (ref. 138 - see below)
Ravenhead refers to Pilkingtons (from 1826) although I'm not sure of the Newcastle company. But what about Chance? It was producing plate glass during this time and had even patented a method. The following is from my proposed second volume on the company:
In May 1841 Chance Brothers were producing 4,000 feet of plate glass per week and further extensions to the buildings were undertaken, along with the ordering of forty-eight new grinders in 1842...
I'll check back to see when it started manufacture of plate glass, but perhaps this report refers to
cast-plate, as opposed to any other form? Rather specific, if it does.
Ref. 138:
A History of Technology, ed. C.Singer et al., vol.IV, 1958, p.368: H.J.Powell, Glass Making in England, 1923, p.123: 13th Report of the Commissioners of Enquiry into the Excise Establishment...Glass, 1835, pp.40,42: Hentie Louw, 'Window-Glass Making in Britain c.1660—c.1860 and its Architectural Impact', Construction History, vol.7, 1991, pp.47–68.