Dr Wall plate? or Chelsea or someone else?

not sure that crescent mark is a Worcester mark:

 

That looks like early 19th century Japanese Imari to me.

Edit, actually the underside perhaps looks more Chinese, so possibly Chinese rather than Japanese, same period.

 

This could well be Worcester. They did so some imari in the early days.

 

John don't the worcester crescents have hatching inside?

 

Not always

 

Oh wow. Thanks John