Bowl, JT mark, I think, 1980.

I love this bowl, it feels like quality. It is very light & nicely thrown. I thought it may be porcelain, but a voice in my head says stoneware. Is this one of those paler stoneware pieces that looks (to me from the unglazed footrim & base) like porcelain? I remember a discussion about this very thing not so long back. Any help appreciated, I would like to know what it is.
The mark looks like a T coming out of the side of a J.
When I picked this up it reminded me of a couple of Alan Spencer Green pieces I was once lucky enough to own. Not suggesting it has anything to do with him.
Many thanks.