THIS chilling picture of a suicide bomber boarding a train bound for the capital will shock Londoners.

The picture released by police yesterday shows 18-year-old Hasib Hussain at Luton railway station around 7.20am, just before he boarded a train to King's Cross station.

The grainy image was captured by CCTV cameras at the station and discoverd by one of the hundreds of police officers scanning more than 5,000 tapes for clues.

Hussain had previously travelled from West Yorkshire and police believe he arrived in London with three other men.

Later he would board a No 30 bus bound for Hackney carrying a deadly rucksack containing a ten pound bomb.

Police are still appealing for assistance in placing his movements between his 08.26am arrival at Kings Cross and the explosion on the bus at 09.47am, almost an hour after his accomplices detonated coordinated devices on Tube trains.

The murderous quartet has so far claimed 53 lives in what became the biggest terrorist attack on British soil.

London and the rest of the UK is still coming to terms with the fact that Hussain, Shazad Tanweer, Mohammed Sidique Khan and a forth bomber were all British-born Muslims carrying out attacks in the name of their faith.

Forensic evidence has confirmed that Hussain died on the bus and Tanweer in the Aldgate Tube explosion.

Kahn's personal documents were found at both the Aldgate and Edgware Road blast sites, but there is no forensic evidence yet that he was killed in either bombing, Met anti-terrorist chief Peter Clarke said at a press briefing yesterday.

Police believe they now know the name of the forth bomber, Deputy Assistant Commissioner Clarke added.

"We have just received forensic evidence which makes it very likely that he died in the explosion at Russell Square."

He urged any of the 80 bus passengers who have not yet spoken to police to come forward.

"The bus started its journey at Marble Arch at 9 o'clock. By five past nine it was in Gloucester Place, and at ten past nine in the Marylebone Road.

"By 9.30am it was in the Euston Road near the junction with Gower Street, heading east.

"The closure of Kings Cross Station, because of the attack on the Underground, meant that the bus had to be diverted from its normal route , to travel south into Woburn Place and Tavistock Square."

DAC Clarke also appealed for witnesses who saw Hussain before he boarded the bus.

"Did you see this man at King's Cross? Was he alone or with others? Do you know the route he took from the station?

"Did you see him get on to a No 30 bus? And if you did, where and when was that?"

Anyone with information can call the anti-terrorist hotline on 0800 789 321