Police officers face a catch-22 situation over dealing with historical sexual abuse claims, the Metropolitan Police Chief Sir Bernard Hogan-Howe has said.
He told the BBC that the police are criticised when they do not take allegations seriously but also condemned for pursuing them.
His comments come after the Director of Public Prosecutions (DPP) Alison Saunders wrote in The Times defending trials in the wake of the Jimmy Savile scandal, including those of DJ Dave Lee Travis and Coronation Street actor William Roache.
Mr Travis was cleared of 12 indecent assault charges dating back to the 1970s, while Mr Roache was found not guilty of historical rape and indecent assault charges.
Sir Bernard told BBC Radio 5 Live: “If we ignore the new claims of historical events, we're told that we are wrong.
"If we investigate to the point of charge - we are challenged - did you go too far? And I think we have got to take these things seriously and the place to test it is called a court."
He added that while he was “comfortable” with the prosecutions already put forward, the police and the Crown Prosecution Service “will always look back and review whether we got it right.”
“One of the difficulties you have of course is a jury gives a verdict not a reason. So what you don't understand is what they didn't find persuasive.”
“We, the police, were criticised 20, 30 years ago that when victims came forward we didn't listen,” said Sir Bernard.
“Now victims are coming forward, we are listening and we're trying to get the evidence together to substantiate the claims,” he added.
Mrs Saunders told The Times: “To those who say recent high-profile acquittals show that police and prosecutors are overcompensating for past failings, I say quite simply that we are not.
"If we took to court only cases where, on the papers, we were certain of a conviction, we would rightly be accused of being over-cautious.
"Justice can only be done if prosecutors remain independent and fair, regardless of who a defendant might be."
She added: “So long as our criminal justice system is working effectively, we will continue to see acquittals in these types of cases. But we are also seeing convictions.”
Mrs Saunders, who took over as DPP in October, also condemned “new myths” that some sexual abuse victims were motivated by money.
She said: “It used to be that if a rape victim wore a short skirt, her credibility was undermined. Thankfully, we have moved on.
”Now we must be careful not to establish new myths that victims come forward only for financial or other motives.“