For what its worth, I have a clear decanter with this form (not the dimples) which is marked Daum. I have also seen another, only decorated with horizontal banding, also marked Daum.
I am not suggesting yours is from that factory, just noting the similarity. A continental form, maybe?
To be honest, had I found your decanter, neither Powell, nor Whitefriars, would have been my first, or even second thought.
Let's see what other folks think.