Honours probe evidence not released

A Scotland Yard report defends the abortive 19-month investigation as "focused and proportionate", and discloses details including that detectives requested a "forensic image" of the Downing Street computer system.

It also criticises the Electoral Commission for failing to provide "robust oversight" of what the legal definition of a "commercial" loan was.

The document, written by one of the senior investigators and seen by the Press Association in advance of its delivery to the Met Police Authority next week, states: "The Metropolitan Police Service remains very strongly of the view that, despite some media comment to the contrary, no material was leaked to the press from within the investigative team.

"This view is further confirmed by the fact that the most significant evidence obtained by the investigation has never appeared in the public domain."

A central part of the Operation Ribble probe was whether the sizeable loans given to political parties had breached the Political Parties, Elections and Referendums Act 2000 (PPERA) because they were not on "commercial terms".

The report, prepared by Detective Inspector David Jones, confirms that the lack of a definition for "commercial" caused "investigative difficulties".

The report said a decision was taken when the probe was launched that there was "no need" for Commissioner Sir Ian Blair to be involved in "specific tactical decision making".

However, it was considered "unrealistic" for him to be kept completely separate from the inquiry, partly because he had "regular meetings" with individuals who may be "either witnesses or suspects".

The report indicated that costs for the inquiry were slightly higher than the £1,396,091 previously disclosed under freedom of information laws, at £1,430,779.