IT is more than six years since the deaths of Diana, Princess of Wales, and her lover Dodi Fayed.

And the conspiracy theories surrounding the tragedy are stronger than ever. Was it just a terrible accident or could there possibly be a more sinister explanation?

On the day that an inquest finally opened into the Paris crash, a national newspaper revealed the identity of the person Diana believed was plotting to have her killed. She wrote in a letter handed to butler Paul Burrell that Prince Charles was "planning an accident in my car, brake failure and serious head injury... to make the path clear for him to marry."

It is an incredible allegation to be placed in the public domain and one which the vast majority of people will consider to be beyond belief.

But in the public domain it is and therefore every effort must be made to ensure that it is thoroughly investigated.

The conspiracy theories are not going to go away. Indeed, they have been fuelled by Diana's chilling prediction that she could die in a car crash. Mohamed Al Fayed is also not going to stop alleging that his son and the princess were murdered.

No matter how far-fetched the allegations may appear to be, a cloud of suspicion has hung over this appalling tragedy for far too long.

Coroner Michael Burgess spoke yesterday of his regret that the inquest could lead to "considerable and possibly unnecessary intrusions into private grief".

That is the case with any inquest: the unfortunate consequence of establishing beyond all reasonable doubt the cause of someone's death and any lessons which may need to be learned.

It is, of course, particularly sad that princes William and Harry will have to endure that intrusion. It is something they have to face but it should have been dealt with much earlier.

With every day that passes, the conspiracy theories are given chance to thrive. Time may be a great healer - but in this case, it is simply adding to the agony.