Hi Christine & Ivo, and thanks for the information.
One thing I forgot to mention is that, when wet, they go clear - I don't know if this is significant!
Another thing I'd like to know is whether they have any value - I sell quite a few bits on eBay and was wondering if I should try them there? I have searched on eBay, but couldn't find anything quite like them.
The auction lot included a couple of nice Whitefriars pieces which I've listed, so I shouldn't be out of pocket if I throw these vases away - they're not really my style - but it would be nice to know if it'd be a mistake to do so!
I guess I'd better get myself a UV lamp, as I quite often find bits of glass!
Thanks again for your help, John.