Recently, the Commissioner of the Metropolitan Police, Cressida Dick, said she had told officers they must have an open mind when an allegation of sexual assault is made and that their role was to investigate, not ‘blindly believe’.

This might seem such an obvious thing to say that one can only wonder what had led officers into doing the opposite.

The answer is child sexual exploitation.

For years, as we know only too well in South Yorkshire, many agencies, not just the police, did not believe what they were being told about the grooming and abuse of young girls in various places across the country. So they did not investigate as they should have done. These were the scandals of Rotherham and Rochdale and people like Jimmy Saville.

But after the truth had come out, and police forces and social service departments realised the mistakes they had made, it created an equal and opposite danger. Some allegations of serious sexual assault were not tested as rigorously as they should have been.

We then had the scandal of trials collapsing because some evidence, such as text messages around the time of an alleged rape, revealed that a relationship was rather different from what the complainant had said.

We get into these difficulties because of that word ‘believe’. It’s a little too ambiguous.

What we need the police to do is to ‘believe’ a complainant in the sense of ‘take absolutely seriously’ what is said; and then thoroughly investigate. This is what was not done all those years ago in Rotherham.

What ‘believe’ does not mean is accepting what a complaint says without that thorough investigation. The reasons for that are clear.

In our legal system, evidence has to be tested and there is a duty on the police and Crown Prosecution Service to disclose any evidence that does not help their case. Otherwise there is a potential miscarriage of justice. ‘We believe you’ cannot mean ‘We believe you therefore we are not going to investigate as thoroughly as we could’. Believe means believe and test.

Victims need to hear the police say, ‘We will believe you’, and know that they will be taken seriously.

The community needs to hear the police say,’We believe you’, and know that this also means that an allegation will be thoroughly investigated.

After years of swinging one way and another perhaps we have finally got the balance right.