Best place to get hard evidence is the certificates for Births, Marriages and Deaths.
Freebmd has an index for the civil registration of Births Marriage and Deaths (England and Wales) from July 1837. http://freebmd.rootsweb.com/cgi/search.pl
Certificates can be bought from the GRO for £9.25. http://www.gro.gov.uk/gro/content/certificates/
The 1911 census quoted by Sumi I have attached as you may be using Rootsweb and not have a subscription to a site which provides such.
Note that to youngest child has "club feet".
The birth certificate of any child should give you the name of its mother.
In theory you should easily be able to locate the marriage of James W RENNICK to an Elizabeth in about 1894 but I don't see it.
The name can likely be spelt in various ways. For example this will be the birth of the daughter Doris.
Births Sep 1902
RENICK Doris Sculcoates 9d 222
Births Mar 1900
Renick Lily Sculcoates 9d 205
Given the ages I would have expected JW and Elizabeth to have had children after 1911 and these would give the maiden name of the mother but I can't see any in Sculcoates.
I see that there are a few Trees on Ancestry with these people and some have JW's wife as Elizabeth CRAVEN but none show a marriage nor have any parents for Elizabeth so I'm dubious about whether she was called CRAVEN. A birth certificate may solve the issue.