Well I'm glad I covered both bases,this was taken post 1902 as that's when correspondence was allowed on the backs of these,although she does look a bit old fashioned in this,and if this is 1910 very old fashioned.
Comparing the 2 which we now know where taken roughly the same time you can see the very different styles of the 2 related women,the younger being much more up to date.
On the back it reads Grandmother Redfern & Alfred,this is where I get confused as you say this was written by your Grandmother & Albert was her brother.Do you mean Alfred? if so this would make her your Great Greatgrandmother.
She looks in her 60's so,do you have a 1xGreatgrandmother Redfern born c.1845/1850 & did she have a daughter born mid 1870's (ish).
jim