I think you may find that his mother was Margaret not Mary
WALTER LITTLE   Christening:  29 APR 1850   Castleton, Roxburgh   
Father:  JOHN LITTLE    Mother:  MARGARET PATTISON  
1851 census for Castleton - all born Castleton
John Little 45 labourer
Margaret  45 
Jane   13 
Mary 10 
Andrew   6 
Annie  4 
Walter   1 
Margaret Ballantyne dtr   21 
Robert Ballantyne 31 son in law
John Ballantyne 8 Months g/son 
Castleton ED 3 Page  17 Line 5
IGI
ROBERT BALLANTYNE    Spouse:  MARGARET LITTLE   
Marriage:  07 DEC 1850   Castleton, Roxburgh 
The following instructions will give you various baptisms etc
PARENT SEARCH ON IGI
http://www.familysearch.org/Eng/Search/frameset_search.asp?PAGE=igi/search_IGI.asp&clear_form=true Input fathers name and surname and  mothers christian name and maiden name  
REGION – select British Isles from the menu
COUNTRY – select Scotland
COUNTY (will appear when you select COUNTRY)  – select Roxburgh
Click SEARCH