Do you have any certificates for them? The dates I can put on are:
(from FreeBMD)
Phyllis Kate, 1887 Pancras
Winifred Frances, 1889 Pancras
Helen Louise, 1892 Pancras
Marie Letty, 1896 Pancras
However, these four children in 1901 appear to be the daughters of:
Charles Courtney, 52, Wheelwright
Phillis A, 35
Phillis K, 13
Winifred F, 12
Charles W, 10
Helen L, 8
Ethel R, 7
Marie L, 5
Dora B, 3
1891, index:
Charles, 1848
Phillis A, 1865
Phillis K, 1887
Charles W, 1890
(marriage of Charles Courtney and Phillis Howe is at 1885 on freeBMD)
and from 1881:
Charles Courtney, 59, Wheelwright
Sarah, 30
Edith, 10
1871 shows:
Charles Courtenay, 49, Coach Wheelwright
wife Sarah, 41
John, 21, Coach Wheelwright
Sarah, 20, Chain Maker
Edith, 11Mo (is Edith really their daughter? Or possibly the daughter of Sarah - her birth certificate is indexed, 1870 Pancras on FreeBMD, this would answer it)
1861 index, Clerkenwell
Charles Courtney, b. 1824
Sarah, 1815
Ellen, 1846
Charles, 1848/s
John, 1850
Sarah, 1851
So I think actually Phylis, Winifred, Mary Letty and Helen Louise, although they were your Charles' granddaughters, were his granddaughters through his son Charles Junior, not through his daughter Sarah (who may still have had an illegitimate child in the form of Edith)
There's a death for a Sarah Courtney, aged 30, Jun 1881 in Pancras, and also, close by, a Charles Courtney, same quarter, aged 57. (When I say close I mean same volume, page numbers four apart). There was a smallpox epidemic in 1881 which may have been the cause.
