Special front door

This is the front door of the house where my mother was born in 1919, in Lewisham. We went there today for the first time. We rang the bell to ask permission to take a picture, and the gentleman who lives there invited us in.
Apparently, the great grandfather of a friend of his used to live in the house next door in the 1920s, so may have known my grandparents.
As always, family history research opens new doors, and reminds me of how we are all connected!