Oh dear, I'm so sorry Barbara,

Mary Ann Amelia was born in October 1841..AFTER the census of that year. I would still have expected her parents to be somewhere in the area though.
There are a lot of Letleys in Kent so maybe they didn't move to London until just before she was born?
This is the birth I have on Mary Anne Amelia Letley:
Registration district St Mary Newington
Birth in the Sub-district of St Peter, Newington in the County of Surrey
No. 250 - Twenty Second of October 1841, 8am, at 31 Camden Street, East Street - Mary Ann Amelia - Girl - father, John Henry Letley - mother, Mary Ann Letley formerly Harris - father's occupation, Butcher - informant, Mary Ann, the mark of Mary Anne Letley 31 Camden St East St. - registered, third December 1841 - George Gill L....? registrar
Thanks for trying for me anyway, I'm sure they'll turn up somewhere
Sylvia