Scotland Yard has refused to apologise to Field Marshal Lord Bramall over a dropped nine-month investigation into historical claims of sex abuse.
The 92-year-old war veteran saw his home raided after allegations were made by one man, known as Nick, before police admitted there was insufficient evidence and announced on Friday night that they had dropped the case.
Assistant Commissioner Patricia Gallan said: "I fully recognise how unpleasant it may be to be investigated by the police over allegations of historic abuse.
"For a person to have their innocence publicly called into question must be appalling, and so I have every sympathy with Lord Bramall and his late wife and regret the distress they endured during this investigation."
In a lengthy statement, the senior officer said police would be put off investigating claims if they had to apologise when inquiries did not end with a suspect being charged.
"The Metropolitan Police accepts absolutely that we should apologise when we get things wrong, and we have not shrunk from doing so.
"However, if we were to apologise whenever we investigated allegations that did not lead to a charge, we believe this would have a harmful impact on the judgments made by officers and on the confidence of the public.
"Investigators may be less likely to pursue allegations they knew would be hard to prove, whereas they should be focused on establishing the existence, or otherwise, of relevant evidence."