"An Englishman's home is his castle" is more than an aphorism. Since at least the 18th Century it's been a statement of legal principle. The circumstances in which the police can invade someone's home are rightly constrained by law.
So, like many, I was astonished last week when the BBC live reported a police raid on Sir Cliff Richard's home.
South Yorkshire Police ran two contradictory defences of their actions, first claiming that the publicity had caused victims to come forward, then saying they were not the source of the leak but felt that they had no choice but to co-operate with the BBC to protect the investigation.
Either way, their conduct is highly questionable. Sir Cliff was not informed about the raid; he has not been arrested, nor even interviewed, still less charged.
It looks as though the police may have been going on a 'fishing expedition' to see if they could acquire evidence they did not have.
This cannot justify the BBC filming the raid from a helicopter, treating the story with a tawdry tabloid sensationalism.
The College of Policing's new guidance, published following the Leveson report, states that "save in clearly identified circumstances ... the names or identifying details of those who are arrested or suspected of a crime should not be released by police forces to the press or the public".
A Chief Officer has to authorise a decision to identify a suspect. I don't think the excuse that the BBC already had some information will wash. Anyway, who leaked it? It must have been someone connected with the investigation.
A police culture that routinely leaks the names of suspects, inevitably followed by a sham statement such as "a 73-year old man has been interviewed", is corrosive. It is a breach of their new code of ethics at least, and corrupt if it involves payment.
As the Leveson report said, "The presence of the press at a high profile arrest ... may ... give rise to difficult issues of fairness within the criminal justice process."
The police should not ignore historic claims of criminal abuse. I don't subscribe to the view that there should be a statute of limitations on these. Justice to the victims requires careful investigation.
The point, rather, is a simple one. Everyone is innocent until proven guilty. If the authorities and the media act in a way which undermines that principle, justice cannot be done.