The clearest image of the man behind the 7 July bomb attack on a London bus has been released by police as part of a new appeal for information about his final movements.
The CCTV image shows 18-year-old Hasib Hussain on the main forecourt at King's Cross railway station, emerging from the doorway of the Boots store at 9am on the morning of the blasts.
Looking relaxed in jeans, a T-shirt and light jacket, his backpack, which was full of explosives, clearly visible, Hussain is seen in the photographs around 10 minutes after identical devices carried by Mohammad Sidique Khan, Shehzad Tanweer and Germaine Lindsay exploded at separate locations on the underground network.
Hussain's own device did not explode until 47 minutes later, killing 13 people travelling on a No 30 bus close to Tavistock Square.
Detectives believe that Hussain had initially planned to board a Northern Line train but was unable to do so because of engineering work at King's Cross. Seemingly unsure of what to do and unfamiliar with the area, he wandered around aimlessly for more than an hour.
He is believed to have left King's Cross and walked towards Euston station, before boarding a bus which became caught up in the heavy traffic that followed the tube blasts. He then got off and boarded the No 30 bus heading south.
It emerged last week that three of the four men behind the 7 July bombings had travelled on London on Tuesday 28 June, to familiarise themselves with the route and the area. They arrived at King's Cross station and spent more than three hours in the capital, checking their timings, security and the layout of the underground network.
For reasons not yet known, Hussain was absent from this trip and this is believed to be the reason he spent so long wandering around. He did not know London well and therefore did not know how close other tube stations were.
One source close to the investigation told The Observer: 'It is possible that he had the notion of striking the transport system drilled into him. When he failed to board the tube train, he decided that a bus would have to do.'
Detectives believe that, by the time he detonated his device, he would have been aware that the other three bombers had carried out their task. Police cars and ambulances were moving around the area and some of the wounded were being brought to the surface at stations in the area where Hussain was.
It is hoped the release of the picture might help to fill in more details of what Hussain did before boarding the No 30. Andy Hayman, Assistant Commissioner for Specialist Operations at the Met told The Observer: 'It is possible that he bought items in Boots or other shops, or that he spoke to people. We would urge anyone with any information to come forward.'
It has also emerged that those in charge of anti-terrorist operations in London are to consider launching a new campaign which helps to alert to public to the threat of potential suicide bombers.
Senior officers are said to be concerned that the current anti-terrorist advertising campaigns focus too strongly on 'IRA-style' threats and the notion of young Muslim men being radicalised in mosques and extremist bookshops.