Hi Penerod, I am related to you through William & Martha.
So far, I've managed to find the following children for William & Martha and as you will see there is a rather large gap for more possibilities. Unfortunately (even with the help of Rootschat), the family appear not to be on the 1861 or 1871 census.
William Charles 1856-1901 (my great-great granddad)
Frederick James 1864-1872
John Walter 1866- (married Emma Doy)
Joseph Henry 01/08/1868 (bapt 04/10/1868 St Philip, Clerkenwell) . Family were living at 1 Wilmington Place.
Louis Vincent 1871
Margaret Eleanor 1872-
Jesse Herbert 1876-1878
Bertram Francis 1878-1879
Rose Adeline 1881-
Hope this is of help to you. Kanskar