I'm not sure if this is Tower Hamlets exactly (apologies if I have impugned some other borough) but a couple of mornings ago I spotted a car with pole extended that was facing east on Tredegar Road E3, seemingly watching the right turn (for westbound traffic) onto Parnell Road.
For the life of me I could not work out (although I didn't have time to stop and look in detail) at what they might be observing although there is a "turn right bay" and as there is a pedestrian crossing about 10 yards into Parnell Road it may be that congestion is caused and they're after people obstructing the westbound lane whilst trying to turn across it.
I've only seen this the one time but thought it may be of interest.