Nice find on the marriage, Andrea - I didn't think of inverting the forenames.   

!  
I'm still looking for Walter in 1891; the 1881 census is available online free at 
http://www.familysearch.org.
Here's Walter as a baby on the 1871 census:
RG10/1060/85/8 - Jenkins Croft, ArdinglyRichard Simmonds  Head  45  Sawyer
Mary Ann Simmonds  Wife  44
Thomas Simmonds  Son  22  Bricklayer
George Simmonds  Son  20  Sawyer
Joseph Simmonds  Son  18  Labourer
Henry Simmonds  Son  16  Labourer
Alfred Simmonds  Son  14 Labourer
Joseph Simmonds  Son  12  Scholar
Ann Elizabeth Simmonds  Dau  10  Scholar
Morris Simmonds  Son  7  Scholar
Alice Simmonds  Dau  4  Scholar
Walter Simmonds  Son  5m
All born Ardingly.    
The IGI (available free at the same site as the 1881 census) has a possible birth for Richard Simmons on 7 Dec 1826: parents James Simmons and Philadelphia.
Trying to see if Richard and Mary Ann's marriage is on Free BMD, but they're updating their hardware at the moment, and the site isn't performing as well as usual - I'm just getting error messages, so will try again later.
Rambler