Thanks for your reply Keith!
Sorry I haven't responded sooner, I've had internet problems. Hadn't thought about Stevens & Williams, my thoughts were going along towards Whitefriars but having looked at some of the controlled bubble work of Keith Murray the quality of the work is certainly similar. I haven't come across a similar shape yet but no doubt seek and ye shall find! You mentioned you have a similar one but I imagine it has a different base? The balled stem on mine is a hard one to match up on the searches I have done 'til now, but I will keep looking.
Thanks again for the information Keith.
Kind regards
Barry