The latest twist in the Davies saga means the full details of the incident on Clapham Common may never be disclosed.

BBC Home Affairs Correspondent Graeme McLagan surveys the case

Mr Davies quit his cabinet post last month and resigned as Labour candidate for the leadership of the Welsh Assembly after confessing an "error of judgement" in the south London park.

He said he agreed to go for a meal with a stranger he met on the common, but was later robbed at knifepoint.

The tabloids went to town after Mr Davies's 'error of judgement'

His statement sparked feverish tabloid speculation but Mr Davies has repeatedly denied sex or drugs were involved.

He has received thousands of letters of encouragement since his resignation, including one from Virgin boss Richard Branson.

'Little prospect of conviction'

The Crown Prosecution Service said on Friday that there was "insufficient evidence" for a realistic prospect of conviction in the case.

Police arrested six people in relation to the alleged robbery, but released all but one after questioning.

Donald Fearon...all charges dropped

Homeless Donald Fearon, 38, appeared in court on 1 November charged with the robbery.

He was remanded in custody by Camberwell Green magistrates without making an application for bail.

The prosecution alleged that Mr Davies had been robbed of his wallet, his Labour Party card and conference pass, his mobile phone and his Ford Granada car in Dray Gardens, Brixton.

'I committed no crime'

In a statement issued by his former special adviser, Mr Davies reiterated that he had committed no crime.

Ron Davies's solicitor Martin Warren speaking to BBC News

He said: "My lapse of judgment was to allow myself to be placed in a position of grave personal danger and become the innocent victim of an horrific crime perpetrated by a cunning and plausible individual."

Mr Davies said: "I accept the decision of the CPS not to proceed with the charge which is clearly an exercise of legal judgment on their part."

Legal Affairs correspondent Joshua Rozenberg says the indications are that charges will eventually be dropped against the five others arrested in connection with the case.

If there is to be no court case then the mystery of the Ron Davies "scandal that wasn't" will never be unravelled.