www.GymRatZ.co.uk wrote:

My speed-school offer was triggered by a local gantry camera.
I'm extremely careful when the "smart" speed limits are up and always
GPS and cruise control however 12:30 Christmas day no speed limit was
shown and in my stupidity I simply forgot about the camera.
The "new" and apparently ultra clever series 3.0 cams (2 x yellow boxes
mounted on the gantry supporting pole) triggered at 81 mph.

If the gantry was displaying 70 or national speed limit my attention
would have been drawn to the possibility of a snapshot but no such clue
was afforded.

I've always treated the M1 cameras north of Leicester and south of
Sheffield as "off", so long as they aren't displaying a number or NSL
symbol, they might have a default limit, but it must be well into three
digits.