In his book, 'Memoirs of a Radical Lawyer', Michael Mansfield has said that the 1997 car crash in the Alma Tunnel in Paris still poses some unanswered questions despite a lengthy inquest at the high court.
The 67-year-old Queen's Counsel, who has represented clients in many high profile cases, has insisted the inquest had not been a waste of time and that Mohamed Al-Fayed was entitled to the procedure as "a grieving father".
In the book, which is being serialised in 'The Times', he wrote: "I found it difficult simply to accept that what happened in the Alma Tunnel in Paris was 'just one of those tragic things'. Of course it might have been, but then that's what 'they' always hope we will think.
"Judging whether a hidden hand is at work is always difficult, but I prefer a healthy and inquisitive assessment of the authorised version, and for me it was mere serendipity to be approached a year after the crash and asked to represent Mohamed Al Fayed for the purposes of an inquest."
Mansfield added: "There is still a widespread belief that the inquest was a waste of time and money and came to no different conclusion than previous investigations and inquiries. This is a serious misconception.
"On April 7, 2008, the jury did not decide it was just a tragic accident, but returned a verdict of unlawful killing by the drivers of both Mercedes and the following vehicles. The 'following vehicles' element in the verdict was an aspect that very few commentators picked up on, or bothered with."
The book has raised issues set out in the trial but not "resolved by evidence, or reflected in the verdict", like the box of missing personal papers of Diana and three hours on the evening of August 30, 1997, during which the movements of Dodi's chauffeur Henri Paul could not be established.
Image: Princess Diana
Windsor by marriage
The Queen: Diana's real story
Diana wrote to butler of plot to harm her in accident
Kalam not qualified to talk about Pokhran: Sethna
Opposition allege cover-up in Kerala murder case