Citroen C4 - 'Speeding' on the motorway - ppfb

Hi
Our car has been snapped doing 66mph on the M62 and I've been sent a notice of intended prosecution as registered keeper. Neither my wife or I are 100% certain who was driving and it's not clear from the three photos available on the police website.
The thing is, obviously 66mph on an m-way is not speeding so I must assume I was passing through a roadworks zone because the prosecution note says 'for exceeding 50mph on a motorway'. Neither my wife or I are given to exceeding the speed limit by 16mph as a rule so it's all very odd.
As I say, we have to assume it was roadworks but is it our job to have to assume this given that one of us will be fined and have points on our licence? If one of us is to be prosecuted, are we not within our rights to expect an 100% accurate description of the circumstances of the speeding before we hold our hands up?
There is NO mention of roadworks on any of the documentation I have been sent and it's not obvious in any of the pictures either. Given I know that speeding tickets on non-motorway thoroughfares have to be 100% accurate, couldn't I simply and cheekily respond by saying 'Exceeding 50mph on a motorway' is not illegal?!
And speaking of accuracy ... the prosecution notice says the car was caught between j23 and j24 eastbound but, although the calibration certificate also says the camera is located eastbound, it also clearly states the location is between j24 and j23 which that way round would be on the westbound carriageway. If the calibration certificate can't get such a basic piece of location information right how can I be expected to trust the rest of the incomprehensible data on it?!
Thoughts on any/all of the above would be appreciated.

Citroen C4 - 'Speeding' on the motorway - LucyBC
Not naming the driver is dangerous as it means they can bring forward a "failure to identify" charge under S172 of the Road Traffic Act which can mean six points, However if you genuinely do not know who was driving the cases can be defended and we win around 90% of those we take. I would need to have a colleague speak to you to assess your prospects for success. Please supply a telephone number. There is no charge for the call.

On the issue of the accuracy of the ticket the police can amend the evidence right up to the time of hearing if it is incorrect so if they can show you were speeding in a roadworks then getting the direction of travel seemingly wrong will not afford you a loophole as they will correct it before trial.