Depends I guess.
Being born in Denmark hill could just be Kings hospital (2 of my 3 kids were born there) which despite being in Lambeth. also covers people living much closer to Lewisham.
Worthingite.
My kids were born in Lambeth/Lewisham and lived in Bromley for most of their lives,
Fortunately they understand that you don't necessarily have to follow your local team.