Sir Gus can't shine light on all aspects of this murky affair

Thank goodness for investigative newspapers. Whatever your views on the Liam Fox affair, make no mistake: You would know almost nothing about it but for the determination of investigative journalists.

There are so many questions still to be answered. What was best man Adam Werritty up to during those James Bond-style trips abroad? Was he acting on Dr Fox's behalf, or acting out some "Walter Mitty" fantasy? And most important of all, who paid, and why? Sir Gus O'Donnell, although a hugely admired figure in Whitehall, cannot give us the answers to all of these questions. The Cabinet Secretary is concerned primarily with whether the Ministerial Code was broken, not an exhaustive trawl through the murk. It is enough for him to establish that there was a potential for a conflict of interest. He is not, for example, able to identify or disclose the full list of donors shown to his officials, apparently under a promise of confidentiality.

This is not to criticise Sir Gus. It is the first time that a Cabinet Secretary's report to a prime minister has been published, so we should celebrate that. But it remains the case that all of the disclosures that led to Dr Fox's resignation stemmed not from official investigations but from newspaper inquiries and revelations.

Among these, the bizarre number of meetings between Dr Fox and Mr Werritty; details of the accounts of Pargav and the donors; the confusion among foreign officials who wrongly thought Mr Werritty held an official position. Much more still needs to be told. Will the Government or Parliament be the agent of disclosure - or will it be left to the press again?

As David Cameron said during the expenses row, sunlight is the best disinfectant against scandal. But at a time when a few newspapers have been rightly condemned for the way that they took private information from innocent people, it is sobering to realise how much we utterly rely on good and fearless journalism to hold the rich and powerful to account.