There's been speculation in "t'other HG forum" that the additional grey post contained an average speed camera, as there is now also one next to the camera outside Stockport Grammar School. In fact these new poles house additional flash units to make the second photo of the "speeding" vehicle clearer.
It's a pity that SMBC can't find a more useful way of spending their money. Note that this was put in place at the end of the financial year, when councils have to "spend or lose" any surplus funds.

See this thread on the camera, which also says that there is another one southbound.