The Glasshouse, founded by Sam Herman in Neal Street as a studio where some of his graduating students from the Royal College of Art could work, developed into an important and influential British studio and moved to larger premises in Long Acre. After many years in that location, it moved to a location in Islington but it closed a few years ago.
During its London incarnations, many significant names in British studio glass had some form of association with it in one way or other. Pauline Solven, one of Sam's first RCA students, was the first manager. Jane Bruce was also one of the early members. By the early eighties the core members were Annette Meech, Christopher Williams, Steven Newell, David Taylor, Fleur Tookey and Catherine Hough. Simon Moore was also a member. From time to time guests such as Charlie Meaker worked there for short periods, and the film-maker, Anthony Stern, walked by one day and was immediately entranced by watching hot glass being blown, to the extent that he enrolled in a course of lessons, applied to the RCA to do a Masters degree and switched careers. I actually took some evening classes there myself, for fun, since in those days I was primarily involved in selling other people's glass, including works by Glasshouse members.
During the mid-eighties Steven Newell, Catherine Hough, and Simon Moore left the Glasshouse and set up their own studio, (Glassworks, London) in Islington. I still have a copy of the estate agents letter asking me for a reference, and my reply, which was obviously sufficiently favourable to enable them to rent the premises! Later on Simon Moore left Glassworks and set up on his own.
The two people who were members of the Glasshouse for almost its entire existence, were Annette Meech and Christopher Williams. After the Islington location closed they moved to France, where they continue to make beautiful glass. http://www.sivignonglass.com/
They would be the best people to advise whether the paperweight shown was made in the London glasshouse.
The history and chronology related above is from memory. Please excuse any inaccuracies.