Princes William and Harry, the Queen, the Duke of Edinburgh, Prince Charles, Prince Andrew and his two daughters, were joined by the Prime Minister, Tony Blair, and his wife.

At the Princess's home at Kensington Palace, and her burial site at Althorp House, crowds have gathered and laid flowers at the gates.

Khalid Javed reports on a day of reflection

The biggest memorial was unveiled at Harrods, owned by Mohamed al-Fayed, father of Dodi Fayed who died with Diana, where an 8ft-high shrine has been built.

The Union flag is flying at half-mast over Buckingham Palace and all public buildings as a mark of respect and remembrance.

In Paris, at the underpass where the Princess was fatally wounded in a car crash, hundreds have paid their respects.

Princes William and Harry said private prayers for their mother Diana at Crathie Kirk in a short service.

Tony Blair arrives at Crathie Kirk

The young princes looked sombre as they travelled from Balmoral to the nearby church accompanied by the Queen and 10 other senior members of the Royal Family.

Inside, local minister, the Rev Robert Sloan, read Psalm 23 - The Lord is My Shepherd, I Shall Not Want - and verses 28 to 31 from chapter 40 of Isaiah - Comfort Ye My People Sayeth Your God.

Princes William and Harry have already thanked the nation for sharing in their grief over their mother's death.

They have asked for privacy to be alone with their thoughts.

The Queen's spokeswoman added: "The Queen and the Royal Family, particularly the Prince of Wales, Prince William and Prince Harry, would like to thank people for their messages and kind gestures of sympathy at this sad time and for sharing their remembrance of the Princess of Wales."

Many messages of sympathy have been received, some on the Royal website.

The Harrods shrine was displayed in the shop's window

At Harrods, an 8ft-high bronze sculpture was put on display.

Two bronze framed photographs of Diana and Dodi, encrusted with seagulls and other birds, are mounted on a plinth above a slowly trickling waterfall surrounded by foliage and four everlasting candles.

In a statement, Mr al-Fayed said: "I believe that anyone who looks upon this memorial will find comfort and peace.

"I pray my beloved son and his dearest Diana have found peace and comfort in heaven. I am sure they are happy together."

Mr al-Fayed's spokesman said: "The shrine symbolises Diana and Dodi's last holiday together, when they were both very happy."

All-night vigils

Overnight, up to 100 people maintained an all-night candlelit vigil outside the gates of Kensington Palace.

Robert Hall reports on the scene at Kensington Palace

They have been joined by thousands who have visited the palace throughout the day to pay their respects.

Floral tributes have also been placed at the main gates of Althorp House, home of Diana's family, and a number of bouquets have been left at the back gates.

Crowds gathered overnight in Paris

At the crash site in Paris people have gathered above the Paris underpass where Diana died.

Britons joined by tourists from around the world laid flowers at the unofficial shrine of the statue of liberty flame above the tunnel.

The only formal indication marking the Princess's death in Paris is the Union flag being flown at half-mast at the British Embassy.

Was she a saint? Calls on BBC Radio 5 Live's Nicky Campbell programme

Diana's brother, Earl Spencer, and her sisters, Lady Jane Fellowes and Lady Sarah McCorquodale, and their families and staff attended a private memorial service at Althorp.

About 40 people gathered for a moving and "solemn" 45 minute service.

One guest told how the congregation had sung three hymns and heard a sermon from the vicar who conducted Diana's funeral service.

Former members of the Princess's staff attended a service at the Chapel Royal, St James's Palace.

The service was conducted by the Sub Dean of the Chapels Royal, the Rev William Booth.