Last week Anna wrote a piece on ‘The fatal conceit of the Police National Database’. It raised concerns about plans to store the details of 10-15 million people in this database, on the basis that there are only 9.2 million people in the UK with criminal records. By implication, Anna wrote, up to 6 million people without criminal records would be on the database. And given the British government’s less-than-stellar track record with data security, this poses a worrying threat to privacy. I stand behind all of that.

However, the National Policing Improvement Agency (NPIA) has written in to say that Anna’s piece contained a factual error that they would like us to clarify. They say Jennie Cronin, director of the NPIA, never said that, “many of these people [the additional six million] are victims”. In fact, they say that victim data will only be held in a limited number of cases, where it relates to sexual offences for which a court can grant a sexual offences prevention order.

I’m happy to admit it when we get something wrong, and I apologize for us putting inaccurate words in Ms Cronin’s mouth.

The NPIA go on to say that holding such victim data is important because it will help the police to realize when vulnerable people are being repeatedly targeted and prompt them to provide additional protection. The example they cite is of a recent Police National Database (PND) search on a victim of domestic violence, which revealed a pattern of abusive relationships across the country. They say that now the police force in question is fully appraised of the situation, they are in a better position to protect her and to “help her to break the pattern of abusive relationships.” Similarly, they believe the victim data on the PND will help police to protect “children and young people being ‘groomed’ for prostitution and then trafficked across local police force borders”.

The NPIA also argue that they are justified to put the details of people who haven’t been convicted of any crime on the PND. They say that individual police forces already hold information on such people, and that all that is in question is sharing it between forces. They also say that Ian Huntley, the murderer of Holly Wells and Jessica Chapman, came to the attention of Humberside Police in relation to allegations of eight separate sexual offences between 1995 and 1999, was investigated in yet another, but was never convicted. They do not claim that the PND would have prevented the Soham murders, but do say it would help to prevent people like Huntley slipping through their net in future.

Now, the NPIA advance valid arguments on both victim data and sharing information on those who have not actually been convicted of any offence. And I think it is important that even those of us are deeply concerned about the over-extension of police powers and the inexorable rise of the database state acknowledge that such policy shifts are often driven by noble intentions.

But I’m still not sold on the whole thing. The trouble is that we’ve been here so many times before: we’re told that new police powers are needed to tackle terrorism, and before you know it they’re being used to arrest people for walking on cycle lanes or heckling at the Labour Party conference. We assume that the police will only arrest you for serious wrongdoing, and then we hear you can be banged up for dropping an apple core and prosecuted for overfilling your wheelie bin.

If I still believed that the police could be trusted to exercise their powers fairly, proportionately, and responsibly, I wouldn’t have to be writing this blog. But I don’t believe it, and many others feel the same way. Whatever the rights and wrongs of the Police National Database, the National Policing Improvement Agency has its work cut out to convince us we’re wrong about that.