a little info, i have a nice VSL vase, signed, I was told by Mark West,website,http://www.markwest-glass.com/index.html
that pre 1950s the glass was not signed, but had a foil label, or marked with a circular acid stamp.
Have a look at the above website, Mark has a lot of nice VSL stuff, i believe he bought the
contents of the VSL factory museum.
I was quite excited because i found an almost identical one like mine on the Mallets antiques
website for $12,000, i thought a good buy for £20, but they are about the most expensive
poshest antiques shop in the world!
Mark still thinks i should still get a few hundred quid for mine, i may sell one day.
Your vase is nice, iwould think post 1950s, but not quite as spectacular as some of their stuff.
I will pop a piccie on of mine in a while.
modifed to add piccie ov VSL vase.(Im quite proud of this one!!)http://glassgallery.yobunny.org.uk/displayimage.php?pos=-4532
Im told mine is probably a Charles Graffart design. I hope this is useful, apologies for showing off
my own piece!