|Police have recovered the four rucksacks and bags left behind by the suspected bombers plus another one found abandoned in bushes in north London.
It appears that the detonators went off - eyewitnesses spoke of a noise like a champagne cork or a firecracker - but the explosives failed to detonate.
Each of the bombs was in a clear plastic food container that police said were manufactured in India and sold in just 100 outlets across the UK.
The "Delta family containers" are described as having six-and-a-quarter litre capacity, made of clear plastic, with a white lid.
Police have appealed to shop owners who may have sold five or more of them together recently to come forward.
Forensic experts are analysing the failed bombs to see if there are chemical links with the 7 July blasts.