the period covered by the Dansk Glas book is a century where, in the U.K., we are poorly served for reference books on drinking glasses. There are many books covering C18 and early C19 glass, but after c. 1830 serious collectors take little interest, which is partly due to the advent of pressed glass, and doubtless affected also by the lack of quality hand made material. Victoria's reign seems to have ushered in the beginnings of utility glass, and you can see why the collectors passion drops away.
quote..............."Drinking glass industry in Finland, in France, in Holland, in Britain and in Germany made similar models. The market demanded, the industry provided. Just the intensity of colour was a very British thing"..........
Whilst there may have been a similarity in many drinking glass shapes throughout Europe during the C19, I wasn't aware that the British made romers/roemers - at least in the traditional C17 German style - the Ravenscroft examples didn't have the German coiled pedestal stem form. I do know that there are one or two alleged dark green examples reputedly British with flatish feet similar to the Ravenscroft pieces - but I get the impression that the German coiled stemmed romer/roemer, was not a shape that the British persisted with - certainly in the C19. I have to say that despite my above comments about E. & L.
roemers, I must admit to not having seen one.

coming back to the comments about zaffre - it would seem that chromium was used as a colourant to produce a good dark green - although I don't think it was used prior to c. 1800, before which the books are telling me that iron oxide and copper were used. So probably much or some of the C19 dark green glass did in fact contain chromium.
Did zaffre produce green as well as blue?? - I had heard of this used to produce the colour Bristol blue.

(that's a smiley by the way - just in case there is any misunderstanding).