The identification is given by a label formerly verso (now on file): John Wood/ 1821/ a portrait of/ Susan Jay and her dog. The donor provided an undated note concerning Susan Jay, saying she became a Catholic convert and entered a convent at Croyden, upon which her father condemned her portrait to the attic; it descended through her younger brother, John Jay, at the death of whose widow the portrait was recieved by Mrs Mason who presented it to Dulwich.
You are all set!
Your first Culture Weekly will arrive this week.