Hi Roy,
I'm pleased I just stumbled on your post. My dad just bought a black one of these to make up a pair only just realising his original one has no feet. There quite big spill vases I think.
While investigating I found a white one in Cyril Manley 's book described as a waxy white. He reckons they could be Derbyshire bros, because of the Greek key pattern however the Greek key pattern seems quite common, all seem to be unmarked. So there are blue, white and black ones.
Cheers Mike
Funnily enough we bought from a Manchester seller so it may not have wondered far. It's now coming south.