Could it be that Rose was born before the parents were able to marry and Florence had been married before?
Marriages Mar 1911
Smith Benjamin G Richmond S. 2a 651
Wiltshire Florence L Richmond Sry 2a 651
Ah no he was a widower so maybe he wasn't able to marry until 1911? https://search.ancestry.co.uk/cgi-bin/sse.dll?indiv=1&db...