The couple's account of how the little girl vanished on a family holiday to Portugal in 2007 was due to hit the shops on April 28 2011, just before the fourth anniversary of her disappearance.

But publishers Transworld postponed the release date by a fortnight after it was announced that Prince William would marry Kate Middleton in Westminster Abbey in London on April 29.

Clash: Kate and Gerry McCann have moved the publication of their book about their missing daughter Madeleine from April 28 2011 so as not to clash with the wedding of Prince William and Kate Middleton on April 29

The book, which is being written by the McCanns themselves and is simply entitled 'Madeleine', will now be published on May 12, the missing child's eighth birthday.

All proceeds from sales of the book will go to the McCanns' official fund to look for Madeleine, which had been in danger of running out in 2011.

McCann family spokesman Clarence Mitchell said: 'The publication date for "Madeleine" has now been moved on to May 12 2011 in the light of the royal wedding and the subsequent media coverage that will generate.

'Kate and Gerry are very happy with the new date, as are the publishers, and it will still be very much tied into the fourth anniversary of Madeleine's disappearance.'

Anniversary: The book, which is being written by the McCanns themselves, was due out on the 4th anniversary of Madeleine's disappearance, but has now been moved to coincide with what would be her 8th birthday on May 12

Madeleine was nearly four when she vanished from her family's holiday apartment in Praia da Luz in the Algarve on May 3 2007 as her parents dined with friends nearby.

Despite a massive police investigation and huge publicity worldwide, she has not been found.

The official Portuguese inquiry into Madeleine's disappearance was formally shelved in July 2008, although private detectives employed by the McCanns have continued the search.