This incident, while seemingly trivial is a perfect example of why all these surveillance and data retention laws are so dangerous.
In fact, it's precisely because this is so (seemingly) trivial that it is also so very, very important because it shows that there are those in our police forces who have truly dreadful judgement when it comes to what is a reasonable use of their powers.
I accept that there are bad eggs/apples in all lines of work and do not wish to judge the entire force by the actions of one vindictive, thin-skinned creep on a power trip.
But . . . there are two very important points that must be noted here. First, even an individual police officer, acting alone, has a huge level of trust placed on him/her and has the power to make life very unpleasant for anyone they have an issue with. This huge potential impact means that it should be a high priority for the police force to identify any such individuals and either correct their behaviour or remove them from positions where they can be dangerous.
The second point is that even if we assume that such police officers do act alone in the first instance, the police culture seems to ensure that they are backed all the way to the courts. Officers abusing our trust in this fashion are not only not disciplined but are actively supported by the establishment.
There is a hugely unequal power relationship between a police officer and a normal citizen and the result of this is that even one problematic constable can cause a great deal of pain and upset and inconvenience and embarrassment for a person. And this is why, despite the overwhelming majority of police officers being good, decent people, we simply cannot trust them - as a group - to exercise their own judgement in these matters.
That an individual officer would do this proves you can't trust individual officers to excercise good judgement in these matters and so must go through approval and oversight. That the police force backed him up proves that they are not a suitable source of that approval and oversight.