Chinese tenmoku style teabowl with Bt mark - Bridget Tennent

The title is to describe the shape, which is what tenmoku originally meant, before it became used for the dark brown glaze.

So I am not suggesting that it is Chinese but have no idea about it, except that it looks at least 50 years old. It's mine but I can't remember where I picked it up many years ago.

Any thoughts?

I believe it's by Bridget Tennent. She was potting in Farnham in the early 90s and moved to London in the late 90s