With regard to the speed cameras we have on our roads today. That is a piece of relatively unsophisticated equipment, just a radar device with a fixed camera and flash. The radar device and the camera provides what is legally seen as primary evidence against you. But the secondary evidence which the police and courts have to have to support what is in effect an allegation not 100% proof of speeding, has to exist.
The secondary evidence is provided by the lines on the road. The police are expected to extrapolate from the photographs count up the distance between the lines in relation to your car as it is crossing them, ie the distance you have travelled in a given time - this indicates your overall speed. This will then be used to corroborate the speed which was found on the radar device. What often happens is that the police do not necessarily always integrate all of this information correctly and there have been hundreds of examples of this where the police do not produce the proper secondary evidence to support the allegations of the primary evidence.
If you do get caught allegedly speeding, and you receive a notice of prosecution through he post you have to make a choice as to whether you are going to accept the prosecution and pay the penalty or penalties, or contest it. This would of course depends on a number of factors, ie if you can afford to hire a solicitor or barrister to advise and represent you in court, and what is often the case, if you have a number of points on your licence already and you are facing a disqualification.
When you do decide to hire a solicitor you need to first of all make sure that they are a specialist in this field. There are a large number of solicitors and barristers who exclusively deal with motoring prosecutions and they are definitely the ones to go to. There will be a massive difference between the quality of representation and advice you will get from a traffic offences specialist and an ordinary general solicitor.
So when you have received a notice of intended prosecution for speeding from the police you will see on the back of the notice what is called a section 172 notice,which is a requirement to identify the driver. The police will tell you that you have a legal obligation to identify yourself in these circumstances but I have been reliably informed by a solicitor friend who does specialise in motoring law, that this is not necessarily always the case.