Metropolitan Police Commissioner Sir Ian Blair said today that the death toll will rise as he paid tribute to rescue workers.
Sir Ian, who carried a large bunch of white lilies, paused for reflection before meeting religious figures at the floral tribute site just outside King's Cross station.
He said he had just come from one of the scenes of the bombing in Russell Square. He said: "I have been down on the tracks and I just want to re-emphasise what a magnificent job the Metropolitan Police Service, the British Transport Police and the City of London Police are doing in what are still extraordinarily difficult conditions.
"I appeal to everybody to give us time. However terrible it is, we must take our time as we go through the identification process. "We will identify people as quickly as we can."
Sir Ian described the areas of investigation as "the biggest crime scenes in English history" and added: "We have got to get this right." He went on: "This is a pitiful example of man's inhumanity to man. I travel on the Tube, I travel on the bus as do you."
"To have a bomb go off in there is absolutely appalling." The commissioner insisted that the police would be "implacable" in tracking down the people responsible. "We know we have the support of Londoners and people around the world to solve this terrible crime."
Sir Ian said the fact that 74 family liaison officers (FLOs) had been appointed did not mean that that was the number of people who had died. He said: "The death toll will rise above 52 but the number of family liaison officers is not an exact science.
"The number of confirmed dead is 52 and that will not rise to three figures." He explained that some FLOs had been appointed to some families that were separated so the number was bound to be higher. Talking about the scene, he said: "I have been told about the bodies piled up in the crowded carriage - you know what happens in a crowded Tube when there is a bomb. "It has been a dreadful scene and it is now getting slowly under control."
Sir Ian said every square centimetre of the tunnels as well as the trains were being scrutinised and warned it would take a long, long time. He said three bodies had been formally identified and police were looking at 2,500 CCTV tapes, following up 2000 calls to the anti-terrorist hotline as well as 115,000 calls to the casualty bureau.
"These people will be caught," he said. Asked what his message was to the people of London, he replied: "Get on the Tube and be vigilant."