dunno about junction numbers but as far as i know there are cameras with no flash, thats why all the traffic moves reall slow, and the limit changes every few miles, i know they are between the M5 junction and the M6 junction atleast
Normally I jump on at High Wycombe which is 6 I think but what an arse. Finding a few things on google which seems to confirm it, just with it supposdly going live on the 1st April thought it could be a joke.