Passengers on the Tube have fallen by up to 30%

Transport for London said that at weekends up to 30 per cent fewer people were using the Tube than average, and on weekdays numbers were down by 15 per cent, a total loss of up to 450,000 journeys a day.

Russell Square station reopened yesterday and the Piccadilly Line resumed a full service. That meant all stations opened yesterday for the first time yesterday since the July 7 bombings.

Police are guarding the entrance to every Tube station and rail station in the capital in an attempt to reassure passengers.

Yesterday saw the biggest turnout of police since the Second World War, with more than 6,000 officers on duty. The sight of armed police has become routine, as are bag searches and continual announcements about security.

Officers were drafted in from across the country and police from Scotland Yard's 500-strong firearms unit, SO19, were guarding key targets. The SAS counter-terrorism unit was on standby.

The Metropolitan Police's Deputy Chief Constable, Andy Trotter, said: "This is the biggest threat London has faced in peacetime and we have to throw all our resources into it." His comments came at a time, when there were concerns about police exhaustion, with all leave being cancelled.

As the number of cyclists carrying briefcases and wearing suits booms, many of them first-time cyclists or people who have not pedalled around the city for at least a decade, roadusers' groups are urging caution. More than 17,000 cyclists were injured on the roads last year, and 134 were killed.