Thank you, Debra. That helped me a lot, but I am still confused ;-)
Let me summarize what I know and what I am still trying to find.
My start is the birth of James George, born 29 January 1849, in reg. dist. St James Clerkenwell. Mother Sarah Kitson. No father is mentioned, so illegitimate. (I have the birth certificate.)
I found James George in the 1861 census, in Islington, with father Frederick Harvey (born ca. 1832, vellum binder), mother Sarah Harvey, and four siblings:
John G (b. ca. 1855 Holborn)
Amelia (b. ca. 1857 Islington)
Emily (b. ca. 1859 Islington)
Arthur (b. ca. 1861 Islington)
I found the family (without James George, who married in 1870) in the 1871 census, still in Islington, with three more children. Father Frederick is still vellum binder.
I looked up these children in the GRO birth data base. James George is there, as he should, with his mother's name only. The others:
John 1856 M [no MMN; all the following have MMN Kitson]
Amelia Elizabeth 1856 D
Emily Charlotte 1859 M
Arthur Wright 1861 M
Anne Louisa 1863 M
Alice Grace 1865 M
Theresa Louisa 1867 S
Louisa Theresa 1867 S
[The Last two are twins; Louisa T died in that same quarter.]
What is confusing is that John and Amelia Elizabeth are born closely together.
John's record does not specify the mother's name. Amelia E and all other children have Kitson as MMN.
The 1881 census (found by Debra) has Head as last name, but the profession of the father is still vellum binder; he is a widower now. The three children still living with him are all present and correct in the list above (Emily [written as Emily Harvey, further evidence that the name "head" is just sloppiness of the census taker], Theresa and Grace).
Debra also found the 1851 census, were mother Sarah has been written with last name "Ward" with her son James G, also last name "Ward". She is reported married.
I am at a loss to explain this situation:
Did Sarah Kitson have her son James George in 1849 before she was married, married then a man named Ward, who died, and then married Frederick Harvey?
I tried to find marriages Ward x Kitson, Harvey x Kitson, and Harvey x Ward, without success.
Any help in clearing up my confusion would be very helpful. (As I said in a previous note, I am Dutch and not well acquainted with British genealogy.)
Also help in finding the birth/baptism of Sarah Kitson would be nice. All the census documents have her born in Suffolk.
(Father Frederick Wright Harvey was baptized 12 Mar 1832 in St. Martin-in-the Fields.)
My apologies for this long note.