The nation fell silent yesterday to remember the victims of the July 7 London bombings, one year after the suicide attacks that killed 52 innocent people.
Survivors, bereaved relatives and emergency workers at the blast sites were joined by millions in offices, shops, factories and homes across the country to observe a two minute silence.
The moment of national remembrance and reflection followed solemn memorial ceremonies at the scenes of each of the bombings to mark their first anniversary.
Over the course of the day, thousands of floral tributes were placed by well-wishers and commuters at the blast sites and at a giant 40ft floral mosaic of purple carnations in Regent's Park.
But as people paid their respects, there was a chilling warning from Britain's most senior police officer, who said it was "almost inevitable" that terrorists would get through and attack Britain again.
For those caught up in last year's explosions, the day held mixed emotions.
At the blast sites, relatives and survivors tearfully hugged one another as they laid floral tributes.
The focal point of the memorial events was the two minute silence which began with the chimes of Big Ben and ended with the bell of St Paul's Cathedral.
Prime Minister Tony Blair observed the silence at the London Fire Brigade's headquarters on Albert Embankment in Lambeth. The Queen, the Duke of Edinburgh, the Prince of Wales and the Duchess of Cornwall were at the Order of the Thistle service at St Giles' Cathedral in Edinburgh.
Home Secretary John Reid joined Metropolitan Police Commissioner Sir Ian Blair and his most senior officers outside New Scotland Yard.
The Prime Minister said: "Today is a day of remembrance across London and the United Kingdom. It is a chance for the whole nation to come together to offer comfort and support to those who lost loved ones or were injured on that terrible day."
The official memorial events began at 8.50am - exactly one year to the minute since three of the four suicide bombers exploded their devices simultaneously on Tube trains across the capital.
At King's Cross, from where the four bombers fanned out that morning, Culture Secretary Tessa Jowell, London Mayor Ken Livingstone, Transport Commissioner Peter Hendy and London Underground managing director Tim O'Toole laid wreaths. They then stood in silence, heads bowed.
At the same time, a bell tolled at St Paul's Cathedral and candles representing the first three blast sites - Aldgate, Edgware Road and Russell Square - were lit.
Just under one hour later, the commemorative events moved on to Tavistock Square, where 13 innocent people lost their lives in the bus explosion.
Mr Livingstone and Mr Hendy were joined by Greek-born bus driver George Psaradakis, 50, who laid a wreath at 9.47am - exactly one year since his bus was ripped apart by Hasib Hussain's rucksack bomb.
In private ceremonies, memorial plaques were unveiled at the five main locations in London: Tavistock Square, Aldgate station, where Shehzad Tanweer detonated his bomb, Edgware Road, where Mohammad Sidique Khan detonated his, and at King's Cross and Russell Square stations - between which Jermaine Lindsay exploded his device.
Security had been tightened across London, amid fears that terrorists could try to use the anniversary to mount another attack. Sir Ian said: "I fear it is almost inevitable that there will be further attacks and almost inevitable that some of those attacks will get through."
Mr Livingstone said the aftermath of the bombings had been the capital's greatest trial since the end of the Second World War.