I am a granddaughter of Marjorie Edith Wood, I enjoyed reading the letters from Annie and Charles to Lillie.
In the 1871 census, William and Caroline Wood had the following:
George Henry, 17, grocers apprentice
William Tho, 15, carpenter
John J, 13, clerk
Edgar I , 11, scholar
Charles, 9, scholar
Their daughters must have left home by then, but they do appear in the 1861 census with the other children except for Charles(not born yet) and are all living in Great Coggleshall
Elizabeth, 12, pupil teacher
Caroline , 11, scholar
In a photo album belonging to Marjorie, I found a photo of a small boy, about 1 -2 years old, with the name "billy"on the back, no idea who it is or how old the photo is, was anyone in touch with her from your family? Bit of a long shot I think!