Yeah that's true. I should know really, my mate's brother works for them. ANYWAY, yes - not regular police and generally going to be tooled up for an operation.
edit - also the rioters appear to be very much predominantly white. Hm!
Possibly entirely unrelated, but very unusual... there were (at least) three dozen police in Croydon town centre this evening.
No signs of rioting or property damage or whatever, though both the shopping centres seemed to be closing early, so maybe something happened/planned inside either/both of those.