It's one guy parking these taxis along that part of Crystal Palace Road. He leaves them there for months at a time, adding a new one from time to time. It's bizarre, as a parked black cab isn't doing what it's intended for: pounding the streets and taking fares. Mentioned before here: http://www.eastdulwichforum.co.uk/forum/read.php?5,1879925,1879925#msg-1879925