QUOTE (TicToc @ Thu, 27 Nov 2014 - 23:27)
What camera are these?
Is it anpr cameras?
Sort of. They're used to enforce the Low emission Zone (LEZ) around London (currently for LGVs and PCVs but being extended to vans and maybe cars one day). Two cameras per lane to catch every vehicle in multi-lane (congested) traffic.
You often see similar camera (two per carriageway) for just anpr (surveillance) purposes on other roads with single / dual lanes and less congestion.