Last week, the controversy over the Princess's death took a sensational turn with the claim by an unnamed French policeman that Diana was, indeed, expecting a child when she was killed.

The officer is believed to have seen the 6,000 pages of French official documents collected on the car crash and Diana's death - technically from heart failure in hospital - four hours later.

His claim is supported by photographs of her wearing a leopard print swimsuit, taken in the South of France just 14 days before she was killed, showing an unmistakable bump around her waistline and what appear to be swelling breasts.

And today the Mail can reveal a further startling claim that, in the days before she joined Dodi on holiday, the Princess went to a leading London hospital to undergo a pregnancy scan.

'Of course, at the time, it was kept incredibly quiet,' said the source, who wished to remain anonymous. 'The Princess might have been divorced, but the idea of the mother of the future King becoming a single mother was too controversial to contemplate.' The mystery surrounding a possible pregnancy, and the further perplexing details leading up to Diana's death, are now to be examined afresh as the Royal Coroner, Dr Michael Burgess, opens an official inquest next month.