1901 Census
14 Chapel Street, Leeds
William Turner, Head, Mar, 49, Laundry Proprietor, London Mid
Caroline, Wife, Mar, 47, Leeds Yorks
Louisa B Turner, Daur, S, 20, Laundress, Leeds
William A Turner, Grandson, 3, Leeds
Of course this may not be them, but I have a strange feeling it is, especially with Williams place of birth.
I honestly don`t know why the change of name, but sometimes it was done for convenience - they may have owed money or didn`t want to be found for whatever reason. It doesn`t explain Louisas father being Richard, but the address on the marriage certainly matches with what you have found.
The mystery deepens!
Mo