Cameras around Heathrow

What's the threshold you get done for by the cameras in the gantries on the M25 around Heathrow? I went through at least one at 80mph (with no variable limit set) this morning and I didn't know about the cameras until someone mentioned them later on today.

There are no cameras! Just the warning signs and the white lines. Not a camera in sight except near the M3/A3 section.

Sorry to contradict you Paul but I went anti-clockwise today and always look in the van mirrors under every gantry and (95% sure) I spotted cameras on one of them. It was further South than Heathrow but I'm sure it was before Staines. I don't pay them too much attention now, just plough on through and check the mirrors for flashes. Bit silly I know but at least I get where I'm going at least 5 minutes quicker!

I've used to do the M25 from Jcn 20 down to 9 very often and have used a road angel and it goes off for each gantry from Jcn 16 onwards. There was an e-mail floating around this year which said that the camera's were going digital. I have been flashed by the camera's twice late evening in a car doing 85+ but never recieved anything in the post!

I'd agree that it does look like they're on more gantries.

I've only done a few runs through there recently so haven't sussed the whole set up yet, but (for those on 11 points ) would suggest to slow down if there are grey camera boxes facing the other way, and keep an eye out when you get close to the gantries as you can usually see the camera through the metal frame.

IIRC there's also one on the gantry just as you're about to come off onto the M4 from the Northbound direction.

All that said I usually get bored and steam through there anyway, but (touch wood) haven't been done yet!