Nick Clegg shifted ground on the Lord Rennard scandal yet again today, this time hinting that the hidden sex scandal was a factor in the peer’s early retirement in 2009.

The Deputy Prime Minister said allegations of improper conduct to women had been “in the background” when it was decided Lord Rennard would step down because of ill health. That contrasted with the official version that he left office for health reasons alone.

In another dramatic change from his indignant reaction to earlier criticism this week, the Lib-Dem leader admitted his party made “very serious mistakes” in the way it handled the informal complaints made by several women.

In a third change of tone, he also praised the journalists who exposed the Rennard scandal, in contrast with his remarks yesterday about “self-appointed detectives” in the media.

“There were some very serious mistakes and the women were not listened to and were let down,” Mr Clegg confessed during his weekly phone-in on LBC 97.3 radio. “I so much believe it is crucial you treat people with respect and dignity in everything you do — and that is what I expect of people in the organisation I lead. That, clearly, did not happen here, to put it mildly.”

His apologetic tone was more in line with party president Tim Farron who admitted on Monday that the Lib-Dems had “screwed up”.

Mr Clegg insists he did not know of any specific allegations — strongly .