I can tell they were the same company by the little animals I have....now have a few extra as well.....and of coure, the Isle of Wight 'Genuine' ones.
I love them all, Isle of wight, Island glass (IOM), and St John's Crystal.....don't mind which label as long as I like the creature.
Guernsey Glass don't appear to have any animals, but do make very pretty 'petal rimmed' glass vases.
That is a nice vase though Chris, I like it very much.
Rosie.