Very large piece of blue slag glass.
I am sure it must be either Davidson or Sowerby but the item is not marked. Looks like it has been used as a flower pot holder for the last few years although I believe it must have been made as a ice bucket wine cooler.
Height 16cm , diameter 17cm and weight a heavy 1.4 kg.
I be interested if any one has seen another or can confirm the maker.
Thanks Roy