Any reason why there is one there for, there are no road works or safety issues there.■■?It is funny seeing cars doing a “brake test” when they see the yellow camera, they think it is a speed camera, and have no idea what “average” means.!!! 
Don’t know the reason but, I know first hand it works!
think they had that many accidents with numptys who don’t know how to merge onto another motorway they just thought “screw this, lets put an average speed camera there to slow everyone down”…
There were roadworks there for a while but when they finished they left the cameras there 
I think there was often a shunt there, which then always screwed the M25, so as previously stated lets slow em all down.
RIPPER:
There were roadworks there for a while but when they finished they left the cameras there
thats all it’s for! 
And it makes some money too.