Hello again Cranstone,
The pictures Jan directed you to, the first three certainly, if you don't know, are of the remaining original buildings that are now part of Downview Prison. Hence the high green fence.
On the first one, the Porters Lodge is the two storey building. The long roof, with the windows and clock tower in it, is new and houses the visitors centre. I still remember having to squeeze up into the top of the clock tower because someone had forgotten to switch on the automatic summer time setting when it was installed.
Regards,
Phil