Had to know who the informant was on Thomas d/c
Informant was 
Jane ASHBY present at death 
19 North Street, Thomas
 son of John BATTY, deceased
So it does look as if mother Marianne on the baptisms of Charles Ashby Batty and Thomas Edward Batty is the daughter of Thomas & Jane ASHBY.
Are there any pieces missing from 1841 census? 
We have deaths at  
18 North Street Charles Ashby Batty on    29th January 1842, informant Catherine ASHBY
19 North Street John Batty on                 12th January 1843   informant 

 BATTY
19 North Street Thomas Edward Batty on 18th May 1843       informant Jane ASHBY
Must have been a very upsetting and distressing time for Mary Ann  
