Thanks for your replies everyone.
I'm sorry that the photos are rubbish and they don't do the bowl justice. It looks a lot better in real life.
It is a lighter grey colour in the ''flesh''. There is a layer of clear glass encasing the grey mottling.
I will try and take some better photos of it tommorrow and try to get better pics of the signature and pontil.
I have seen some Gray_Stan glass on the internet when I googled it but they all seem to be vases and more colourful.
I haven't been able to find any like this bowl which I think is a powder bowl as Paul says.