Hello Jean,
You should know that there is no such thing as a straightforward family.
After finally finding that Sidcup comes under Foots Cray, I couldn't get any further in working out where Ernest came from- and I did try.
I can't find Erith Villa mentioned by name on the 1881 or 1891 and due to the amount of development and different enumerator's routes, it's difficult to pinpoint exactly.
In 1881 there is a Charles Marshall and his wife, Lydia, living in about the right place. I've tracked them back to 1851, with the exception of 1861, and up to 1891. I can only find one child, Jane, born back in 1846, in 1851 and a grand-daughter, Frances Stone, born 1875, in 1881.
I can't find any trace so far of John Henry and Marianne, including a marriage.
Have you got any further?
Happy Christmas,
Phil