More help needed please - this time for James' wife, Sarah.
I applied for what I had thought was their marriage certificate, but found it was not the right one. Now I'm stuck. I have lots of clues for Sarah, but I cannot find a marriage and therefore her maiden name

Sarah (no middle name mentioned anywhere) was born according to the 1891, 1901, 1911 censuses and death register between 1851 and 1857.
She was born in Greenwich, but the 1911 census has Woolwich crossed out and replaced with Greenwich so I'm assuming this is the registration district and not the actual birth location.
The 1911 also states James and Sarah had been married for 31 years.
The Wilson family were travelling in the the South East of England (mainly London, Kent and Sussex) but I cannot locate James and Sarah's marriage.
I really have hit a brick wall with this one and would be grateful for any suggestions.