A car bomb defused in central London today was packed with petrol, nails and gas canisters, police said.
Deputy Assistant Commissioner Peter Clarke, head of Scotland Yard’s counter-terrorism command, said: "It is obvious that if the device had detonated there could have been significant injury or loss of life."
Bomb squad officers defused the bomb after police received reports of a suspicious vehicle in the early hours close to the Tiger Tiger nightclub in the heart of London’s West End.
Mr Clarke said an ambulance crew in the area reported that there was smoke inside the car.
He said it was too early to speculate about who was involved and he called on the public to remain vigilant.
Police will be scouring CCTV footage from the scene of today’s discovery but will also be checking images from further afield, experts said today.
Clues as to when the car travelled into the area, just yards from Piccadilly Circus, could be contained on cameras used to monitor the congestion charge, they said.
Those cameras are known to run 24 hours a day and will provide valuable back-up to images obtained from the scene.
Tapes from private venues such as theatres, clubs and restaurants will also be viewed by police alongside those owned by Westminster City Council.
A total of 160 cameras are run by the council across the whole of Westminster, with their CCTV centre based at the Trocadero.
Congestion charge cameras monitor every entrance and exit to the charging zone and also monitor journeys made within the zone, according to the Transport for London (TfL) website.
Each camera site has at least one colour camera plus a monochrome camera for each lane of traffic being monitored.
The cameras are similar to those currently used in ports and airports - providing "high-quality video signals" to Automatic Number Plate Recognition (ANPR) software, which reads and records details of each vehicle.
Peter Fry, director of the CCTV user group, which provides advice to managers and staff of CCTV operations, said police regarded the cameras as a "third forensic discipline" alongside fingerprinting and DNA.
"Officers will be looking at every single camera in the area and trying to get hold of as many tapes as they can," he said.
"With the July 7 bombings they had more than 100,000 tapes to look at - it’s a massive, massive task."
Mr Fry said he believed CCTV had revolutionised the way police investigations were carried out.
But, he added, the discipline had become more complicated in the last five years owing to digital recording, which meant images were now contained on numerous formats. The quality of images also varies widely, he said.
"You can set cameras to wide angle or put them on a more narrow focus which enables you to get a good view of head and shoulders.
"In the Underground, the cameras were on a close focus whereas for a street scene, the camera will be focused more widely.
"The police may see an image on a wide angle and then go to all the other tapes to find that person on a more narrow angle. It’s about piecing it all together."
Mr Fry estimates there are 1.5 million cameras trained on public spaces across the UK. In addition, many more cameras cover private property, he said.
Stuart Dredge, editor-in-chief of the Tech Digest news blog, said today’s events showed the importance of CCTV cameras.
"People do worry about always being on CCTV but this situation makes them think that it’s not such a bad thing," he said.
"There will be many cameras in that area which may help police - this is the positive side to CCTV.
"It will be like watching a DVD when they piece all the images together, there will be many different angles to look at.
"Assuming the car came through the congestion charge zone, police will also be able to examine those tapes to see if they can identify it.
"People are getting much more used to seeing CCTV images, it’s not just on Crimewatch anymore."