7/7 inquests: CCTV footage captured bombers' preparations on day of attack

Footage of one of the July 7 attackers calmly rummaging around in his rucksack bomb as commuters walk nearby was played at the inquests into their victims' deaths tonight.

Hasib Hussain, 18, was captured on film walking around London's King's Cross station before boarding a number 30 bus and killing himself and 13 others in Tavistock Square.

Investigators compiled footage tracking him emerging from the Tube, joining others attempting to escape the travel chaos and wandering around the busy concourse.

Coroner Lady Justice Hallett watched as he attempted to telephone fellow bombers Mohammed Sidique Khan, 30, Shehzad Tanweer, 22, and Jermaine Lindsay, 19.

But he gets no answer as they have already detonated their home-made bombs on Tube trains near Russell Square, Aldgate and Edgware Road stations.

In extraordinary footage, Hussain can then be seen pausing in the doorway of a branch of WH Smith for two-and-a-half minutes to apparently remove a battery from his device.

He buys a 4.49 9-volt replacement and heads to a nearby branch of McDonald's, where police believe he spent eight minutes inserting the new battery into the bomb.

Hugo Keith QC, for the inquest, said: "He spends a very significant amount of time rooting around in a rucksack containing a highly unstable, cooled explosive mixture."

Detective Inspector Ewan Kindness, of Scotland Yard's Counter Terrorism Command, said when Hussain stands up again, something is in his hand.

He said: "We believe it to be the batteries from the device, but it is difficult to be 100% sure from the image."

The fourth day of the inquests into the 2005 atrocities, sitting at the Royal Courts of Justice in central London, heard more evidence of the huge CCTV trawl undertaken by police.

Hussain was first filmed at 8.54am walking out of the Tube station alongside hundreds of others being evacuated as the emergency becomes clear.

One witness has told the inquest how she nearly walked into him as he sat on a northbound Northern Line platform with his elbows on his knees at about 8.40am.

The terrorist was caught on a large number of cameras in the surrounding streets, station itself, businesses and even cash dispensers.

Wearing a grey fleece jacket and carrying a large navy jacket, he puts on his sunglasses as he walks away and emergency vehicles called to the explosions race past.

The bomber eventually catches a number 91 bus before transferring to a double-decker number 30, destined for Hackney, at Euston bus garage.

Police used footage from other buses to monitor its movements and said a distinctive advertisement for horror film The Descent helped to identify it.

Sitting at the rear of the upper deck, Hussain detonated his bomb at 9.47am, almost exactly an hour after the first three blasts, at the junction of Tavistock Square and Upper Woburn Place.

One bus camera shows debris and smoke flying into the air, while footage from the nearby Ambassador Hotel and British Medical Association reveal people diving for cover.

On a packed route 56 bus, which travelled alongside the stricken bus for several minutes, passengers can be seen looking out of the rear window before rushing to get off.

The coroner was also shown footage from a platform at Liverpool Street station, showing the aftermath of the explosion caused by Tanweer.

Around 40 seconds after the Aldgate service moves off, smoke can be seen billowing back towards the platform as passengers walk off and two police officers investigate.

The inquest heard that documents found at the plotters' bomb factory in Alexandra Grove, Leeds, suggested that they may have been planning to target BBC Television Centre in west London.

Train tickets recovered from the property indicate that Lindsay carried out a series of reconnaissance missions in the capital between January and April 2005.

Earlier today, the inquest heard how the al Qaida-inspired terror cell evaded detection by using unregistered pay-as-you-go mobile phones which they changed regularly.

A police expert said they employed counter-surveillance "tradecraft" to ensure they were not monitored, including separate personal and operational phones.

Detective Sergeant Mark Stuart, of the Metropolitan Police, said almost 4,500 requests were made to mobile phone companies by officers investigating the attacks.

Police were able to recover data from Lindsay's phone, including the SIM card number and text messages that he received and sent.

The inquests have heard the terrorists may have planned to carry out the bombings 24 hours earlier, when the capital was due to learn whether it had won the 2012 Olympic Games.

Plot ringleader Khan visited Dewsbury Hospital in West Yorkshire with his wife, Hasina Patel, on July 5 because of complications with her pregnancy.

Khan apparently postponed the planned attacks in a text message to Lindsay at 4.35am on July 6 which read: "Havin major problem cant make time will ring ya when i got it sorted wait at home."

Lindsay replied at 4.41am: "No bulls*** doctor! fix it!"

On the morning of July 7, Khan, Tanweer, and Hussain drove from their bomb factory in Leeds to Luton railway station, where they met up with Lindsay and caught a train to London.

Within three minutes of 8.50am, Tanweer detonated his bomb at Aldgate, Khan set his device off at Edgware Road and Lindsay blew himself up between King's Cross and Russell Square.

A total of 52 innocent people were killed and more than 700 injured in the attacks, the worst single terrorist atrocity on British soil.

The inquests were adjourned until Monday.