Hi,
I think this is Edward's birth found at the GRO site spelt HARRIE

Edward James Roland HARRIE Dec Q 1907 Bethnal Green 1c 159
mmn: LAMBERT
there are also these possible sisters,
Minnie Louisa HARRIS Sep Q 1905 Bethnal Green 1c 147
mmn: LAMBERT
Alice Ivy HARRIS Mar Q 1910 Bethnal Green 1c 153
mmn: LAMBERT
This would fit with a family in found in Bethnal Green in 1911,
https://www.familysearch.org/ark:/61903/1:1:XWG1-MSM(Shoreditch has been added to the birthplace of Edward Snr and " down the other family members later in a different pen). I wouldn't be sure that it is right.
Looking at that this could be Edward's parents marriage,
Edward William HARRIS Mar Q 1905 Bethnal Green 1c 236
Alice Louisa LAMBERT
St Philip's Church, Bethnal Green
26 Feb 1905
Edward William HARRIS
31
Bachelor
Shoe maker
70 Clifton Buildings
Father: Henry Ephraim HARRIS (deceased), Tailor
Alice Louisa LAMBERT
20
Spinster
Machinist
34 Culham? Buildings
Father: Henry William LAMBERT (deceased), Packing case maker
Witnesses: Lewis Alfred HARRIS, Mary Ann LAMBERT
I expect you have found Florence's divorce,
http://discovery.nationalarchives.gov.uk/details/r/C8025420This was in 1920, maybe it would be worth getting a copy as it might explain why Hilda and Vera didn't live with her. I wonder why she didn't marry Lancelot until 1943?
Regards,
Daisy