This is not an overly dramatic title. This genuinely is a door to the bunker. The bunker is under Kenley aerodrome (also known as RAF Kenley).
Kenley Aerodrome is only a stone’s throw from my house in Caterham, Surrey and a great venue for walking or riding. I understand that pilots would shelter in these bunkers, which were only metres away from where planes would be hidden under scrim.