So the Rock Studio was literally that!
I too wondered about Thomas if that was his burial. he could of course, have been a journeyman.
When would you say the photo might have been taken. John and Martha's first born was Martha in 1866. She was, I believe a twin to Emma who died within the next quarter 1866. I assume it is their first born otherwise other children would be present usually. The last child was born 1879 Emma Jane but as far as I know clothing etc would not have changed much during this time.
Does anyone know when both the Royal and Rock studios were up and running as this might help? In the meantime I'll assume the photo is of their first born.