As part of the operation, two homes that belonged Lord Brittan were searched in 2015, weeks after his death.
Sir Richard's report said the police looked at correspondence, including condolence notes sent to Lady Brittan, as well as searching the properties’ gardens. The district judge who issued the search warrants later said police had “misled” him.
In another operation investigating a historic rape claim made against Lord Brittan, the peer was questioned while he was ill with terminal cancer. He died before he could be informed he had been cleared of that allegation.
The officer in charge of both operations has apologised for what he described as “the distress that has been caused to innocent people and their families".
A close friend told the Daily Telegraph it was an “incredibly difficult and distressing experience” for the peer’s widow.
"The failings of the police are clear for everyone to see in the report from Sir Richard Henriques and the account of Howard Riddle, the former district judge who says he was misled by police during Operation Midland”, they said.
"Yet the IOPC has found that nobody is to blame. Either the system is fundamentally flawed or we have reached a stage where innocent people can be traduced and have their lives ruined by the Metropolitan Police with complete impunity."
