The Queen is due to lead a national memorial service in London dedicated to the victims of the 7 July bombings. Relatives who lost loved ones, survivors and members of the emergency services will join a 2,300 congregation at St Paul's Cathedral at 1500 GMT.
Tony Blair and the Archbishop of Canterbury will also be among those at the service, where candles will be lit to mark the four bomb sites.
The attacks by four suicide bombers killed 52 people and injured hundreds.
Among those attending will be Cathy Johnson, from Nottinghamshire, who lost her 38-year-old husband, Adrian, in the Piccadilly Line blast.
Mrs Johnson, who has a son and a daughter aged nine and six, said it would be good to meet the other families affected, some of whom she had had contact with on the internet.
"It is going to be quite difficult, but it's important for all the families to get together," she said.
Survivor Rachel North said the service would be an important way for her to grieve.
"I grieve every day and I think the service is going to be a very important way for me to feel my grief and to be marking this terrible loss of life with other people," she said.
However, some relatives criticised the way the service had been organised.
Marie Fatayi-Williams, whose son Anthony died in the Tavistock Square bomb blast, said she had received a letter asking if she would like to contribute to the memorial service.
However, when she requested that the hymn Magnificat be included, she did not hear back.
Seven-year-old Ruby Gray, from Ipswich, whose father Richard was killed in the Aldgate blast, is set to present a posy to the Queen. But Ruby's 11-year-old brother, Adam, has refused to attend the ceremony because he blames the prime minister for making London a terror target, the Evening Standard reported.
The ceremony will be conducted by the Dean of St Paul's, the very Reverend Dr John Moses.
During the ceremony, London Mayor Ken Livingstone will read the lesson and the Archbishop of Canterbury, Dr Rowan Williams, will give a sermon.
Religious representatives from a wide range of faiths and members of relief agencies will also gather in memory of the victims.
Four candles will be lit to represent King's Cross, Aldgate, Edgware Road and Tavistock Square - the scenes of the four bombs which exploded during the morning rush hour.
After the ceremony the Queen will meet some of the relatives of those who died, reports BBC news. I.L.