What is the “Tidswell” Bow phase people mention, and what object anchors it?

Some specialist articles divide the production of late Bow porcelain into phases associated with owners or partnerships. One well-known documentary source is a soft-bodied cup dated 1772, which is associated with the Tidswell period. For collectors, the label is not the only thing that matters, it is also evidence that Bow type porcelain continued to be produced until the early 1770s.