Margaret, you might find this useful for economy value u.v. torches... www.netpcdirect.co.uk
I suspect that Lustrousstone is correct (this lady is very clever), but if it does happen that you don't resolve this one - insofar as being able to discount Davidson - then remember you can always contact Val and Chris Stewart on 'info at cloudglassdot com'......(replacing with the correct @ and .com) - who are most likely to be able to provide the answer (at least regarding Davidson products).
'Feeling' for Rd Nos. is a reliable means of detecting them - on clear glass especially - but they can sometimes be indistinct and worn, and pressed glass can sometimes, by its nature, be rough to the feel. I might suggest you supplement feeling by also looking.