Hi,
Sorry can't see John Watts and family in 1841, so possibly in Ireland
I did find a Mary and Maria Watts in what looks like a private school with 9 pupils & 1 servant but impossible to tell if connected:
1841 HO107/665/2 Folio 44 Page 2
2 Skinners Place, St Mary Islington, Finsbury, Middlesex
In house hold of Charlotte Wells, 40, Independent
Mary Watts 13 Pupil not b. in county
Maria Watts 9 " "
Not knowing the son's full name makes it difficult to look for him, but guessing at John after his father, couldn't spot a suitable candidate
Barbara