I think a "book" price of £1000 is rather over optimistic............the ebay price I gave you is about the norm, although in a Collector's centre I would expect a higher price. I have the 15" inch version and they are very striking vases. Yes I would agree some of the glass post war up to when the textured stuff evolved, is very undervalued although I see signs of it coming into its own now.
I recently put some groups of this period on My Gallery on
www.whitefriars.com, if you'd like to take a look, it is at the bottom of the page
http://www.whitefriars.com/my_gallery.php?Owner=Emmi+Smith