You posted a similar request on another board a couple of days ago and someone replied:
"In 1911 living at 60 Beresford Street, Woolwich, which looks like some kind of Lodging House for single men there is a Henery Newman, 38, Single, General Labourer, said to be born at what looks like Midalsford, Cambridgeshire.
As far as I am aware there is no such place but it is possible that someone could misinterpret Whittlesford if the name was spoken in a South Cambridgeshire accent."
Plumstead and Woolwich are next door to each other
With a common name like Brown you have your work cut out, and it could prove to be expensive buying certificates at £9-25 a pop. There are a number of Gertrude M Brown deaths where the implied birth is 1885. But even if you bought the certificates and they were spinsters you still won't know if it's your Gertrude. Marriages could be more positive, as the father's name is given. There are any number of Gertrude M Brown marriages 1911-1915, and even more post 1915.