I know what we're arguing here is semantics in any other context, but in the context of a glass website centred on research it matters who actually made the glass rather than the veracity of the design when it is reproduced by other companies.
So for purposes of research and reference I think it's important to dilineate original Kastrup/Holmegaard production from those produced by other companies, as these vases have their own history to be uncovered.
And even old versus new production within the same company matters, as you pointed out - you've probably noticed as a dealer that it's easier to sell, for example, old Danish-made Arne bowls than it is to sell newer poorer-quality Provence bowls outsourced to Poland because educated collectors know to differentiate between them.
I am in it for the history of Danish Glassworks and being a small country actually none of the glassworks back in time do have been mixed together or taken over by the major glassworks and they have changed name several times and also part of production have been moved from en factory to another together with employes.
Holmegaard Glasswork did found Kastrup Glasswork in 1847.
Odense Glasswork was founded in 1873 but went bankrupt and was bought in 1890 and now with the name Fyens Glasswork, in 1899 they bought Rosdala Glasbrug, Sweden.
In 1907 did many Glassworks in dk merge it was Fyens Classwork (with Aarhus Glasswork that Fyens has bought earlier), Kastrup Glasswork and Hellerup Glasswork the year later also Aalborg Glasswork was part of this merger.
After this there were only to major Glassworks in dk Holmegaard Glasswork and the merge company Kastrup Glasswork (consist of Aalborg, Aarhus Glasswork in Jutland - Fyens Glasswork on Fyhn - Kastrup Glasswork and Hellerup Glasswork on Sealand.
That brings me back to the Otto Brauer gulvvases because he is from Fyens Glasswork and the gulvvases has been produced at that factory, so gulvvases with Kastrup labels is not produced on the Kastrup Glasswork but on Fyens Glasswork but they still are Otto Brauer Design as well as that if Cascade has license to produce Otto Brauer design in uk, thats the history point of view and not the money point of view.
Think collectors mostly would like to have items as close to design year if possible if not unika items, but I also think that a collector of gulvvases would like to have/shown the range of for instance gulvvase to view the historical span.
I am not sure that high price allways state originality, rare, unike, one of a kind could simply also be that is a trend that many wants, maybe in some years time your UK Cascade will be the trend and not low end.