The result will be the kind of celebration of her life that Diana herself may have wanted: sad, emotional but not overly ceremonial. Perhaps significantly, no members of the Royal Family will speak, though the Queen, Queen Mother and Prince Philip will be in the front row of mourners.
The Very Rev Dr Wesley Carr, Dean of Westminster, who will conduct part of the service, said it would contain quiet, reflective time to allow people to mourn her loss; secondly a chance would be given to offer thanks for her "many gifts"; finally, there will be a commitment to the causes that Diana espoused. Once again the Palace insisted it was a "unique" event for a unique person.
The 50-minute ceremony will contain traditional elements, including hymns and the National Anthem as reminders of her Royal status. But the highlight of the non-traditional parts will be Elton John singing a specially amended version of his song "Candle in the Wind".
The words - still being finalised, though a version was available yesterday - are a dedication to Diana, starting "Goodbye, England's Rose; may you ever grow in our hearts". They replace the words of the original which were written as a tribute to Marilyn Monroe and read "Goodbye Norma Jean, though I never knew you at all ..."
The tribute will be given by Diana's brother, Earl Spencer. Her two sisters, Lady Sarah McCorquodale and Lady Sarah Fellowes, will read poems, and Tony Blair will give a reading from I Corinthians i,13.
But, after discussions between the two families, there will be no formal participation by any member of the Royal Family.
Dr Carr explained the reasoning behind the choice of personnel, saying: "We are remembering a particular individual in a private funeral which is very public." He emphasised that it was not a state occasion.
In The Bidding, the Dean will tell the 1,900-strong congregation, which will include many friends of the Princess from all over the world, including fashion and pop stars, that Diana "profoundly influenced" the nation.
"She kept company with kings and queens, with princes and presidents, but we especially remember her humane concerns and how she met individuals and made them feel significant. In her death she commands the sympathy of millions," he will say.
Later, the Archbishop of Canterbury Dr George Carey will lead the prayers, including one for Prince William and Prince Harry "who mourn the passing of their dearly beloved mother".
He will also refer to the other victims of the crash early last Sunday that claimed her life. "We remember too her friend, Dodi Fayed and his family; Henri Paul [the driver] and all for whom today's service rekindles memories of untimely grief," he will say. The Archbishop will then recall the work the Princess carried out with those suffering from Aids and her "compassion for those maimed through the evil of land mines".
The service will end with music from the composer John Taverner, which will "fade into silence" as a prelude to a minute's silence. The end of the silence will be marked by the ringing of the Abbey bells.
At a press briefing yesterday, a Palace spokeswoman said no decision had been on whether Princes William and Harry, or their father Prince Charles and members of the Spencer family, will walk behind the cortege on the way to the Abbey.
In particular, it had to be assessed whether the two boys were up to the "ordeal" she said.
Both families have requested that no photographs or television shots should be taken of them during the service - other than of those giving readings.
The coffin's journey to the Abbey, likely to be watched by more than six million people en route, will begin at 9am on Saturday when it is placed on a gun carriage drawn by three pairs of horses from the King's Troop, Royal Horse Artillery, with 12 bearers from the 1st Battalion Welsh Guards. The Royal Standard will cover the coffin, with family wreaths on top.
There will a mounted police guard, but no other troops and no trumpets or fanfare; the 1-hour-47-minute procession will move in silence. However, the the Abbey's Tenor Bell will be tolled every minute. No time scale has been given for the later procession to the Spencer Chapel in Northamptonshire.
The full guest list may be announced later today, but Lt Col Malcolm Ross, Comptroller in the Lord Chamberlain's office, said the number of official dignitaries had been "greatly reduced" to allow more people associated with Diana's interests and life to attend.
Elton John's Candle in the Wind for Diana
This is the new version of "Candle in the Wind", by Elton John and Bernie Taupin for Diana, Princess of Wales's funeral.
Goodbye England's rose;
may you ever grow in our hearts.
You were the grace that placed itself
where lives were torn apart.
You called out to our country,
and you whispered to those in pain.
Now you belong to Heaven,
and the stars spell out your name.
And it seems to me you lived your life
like a candle in the wind:
never fading with the sunset
when the rain set in.
And your footsteps will always fall here,
along England's greenest hills;
your candle's burned out long before
your legend ever will.
Loveliness we've lost;
these empty days without your smile.
This torch we'll always carry
for our nation's golden child.
And even though we try,
the truth brings us to tears;
all our words cannot express
the joy you brought us through the years.
Goodbye England's rose,
from a country lost without your soul,
who'll miss the wings of your compassion
more than you'll ever know.
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