Coming back from the m23 j11 meet (nice to see you chaps btw) and on the m25 most of the overhead gantries had a beige arm type thing with what looked to be a camera on top - is that they are, just video cameras?

 

Could be wrong (and not for the first time) but they might be the sensors for the Traffic Master system

 

Most of the M25 gantries between 11 and 16 have working (my detector picks them up) Speed cameras. They are hidden in the gantry. The ones you refer to are probably traffic cameras.