MI5 could have "hit the jackpot" of learning the 7/7 ringleader was a committed jihadist if it had followed the intuition of one of its officers, an inquest heard today.
Two months before the July 7 2005 London bombings, a member of the Security Service flagged up information that could have identified a British man who received terrorist training in Pakistan as Mohammed Sidique Khan.
Patrick O'Connor QC, counsel for the families of those killed in the attacks, suggested MI5 could have made the link simply by trawling through an airline passenger list.
"Then you come across Mohammed Sidique Khan and you've hit the jackpot," he said.
But a senior MI5 officer, identified only as Witness G, said it would have been "unusual" to follow up the lead because a key informant had already failed to identify Khan.
In early 2004 counter-terrorism officers watched, followed and photographed Khan, 30, and his deputy, Shehzad Tanweer, 22, travelling from Leeds to meet a group of extremists planning a fertiliser bomb attack, but did not fully identify them at the time.
Separately, MI5 received information from al-Qa'ida supergrass Mohammed Junaid Babar in April 2004 that two men from West Yorkshire called "Ibrahim" and "Zubair" had travelled to a terrorist training camp in Pakistan the previous year.
Babar was shown surveillance pictures of Khan and Tanweer in August 2004 but failed to identify them, and it was only confirmed after the 7/7 attacks that "Ibrahim" was Khan.
Investigators discovered "Ibrahim" had breakfast at Islamabad airport in Pakistan with a member of the fertiliser bomb plot called Jawad Akbar on July 25 2003, the inquest heard.
Mr O'Connor suggested MI5 would have come up with Khan's name if they had checked the passenger manifest of the flight from the UK taken by Akbar.
Witness G replied simply: "I can see your logic."
In May 2005 a Security Service officer flagged up the Leeds-based men - including Khan and Tanweer - seen meeting the fertiliser bomb plotters as possible candidates for "Ibrahim" and "Zubair", the inquest heard.
Witness G said: "That was an intuition by the desk officer at the time, who remembered the northern figures who had been in Crevice."
Mr O'Connor put it to him: "Do you agree, if that intuition had been taken this one step further of trawling through Jawad Akbar's flight, one would have reached the jackpot?"
The senior MI5 officer replied: "If it had worked out in that way, yes.
"It would have been unusual to work further on that intuition because of the strong contra-indication that the men referred to as the three Leeds-based individuals had been shown to Mohammed Junaid Babar and to the second detainee, who had not identified them."
MI5 bugged fertiliser bomb plot leader Omar Khyam boasting that he had four terrorist cells, any of which could carry out an attack if one failed, the inquest heard.
Mr O'Connor suggested that Khan and Tanweer could have been one of these cells and argued that the 7/7 bombings might have been thwarted if they had been put under extensive surveillance.
Khyam was bugged on February 20 2004, apparently talking to a Canadian bomb expert called Mohammed Momin Khawaja who had flown over to visit him.
A Security Service monitoring note from the time recorded that he said: "One cell goes down won't affect other one, we've got four. Don't mix people up."
Police and MI5 voiced fears about these comments at executive liaison group (ELG) meetings to share intelligence about the investigation into the plot, known as Operation Crevice.
The ELG report for February 21 2004 noted: "It is a real possibility that planning for more than one device is under way."
The inquest is looking at whether MI5 could have drawn together intelligence about Khan and Tanweer's links with extremists and established that they were planning mass murder before the 7/7 attacks.
Mr O'Connor suggested that the Security Service should have made "proper assessments" of the pair after they made a series of trips from their homes in Leeds to meet Khyam in Crawley, West Sussex.
He said: "I suggest greater measures could and should have been taken against particularly Mohammed Sidique Khan, including monitoring his travel and taking possible intrusive authorised intelligence measures against him after his return from Pakistan and successfully thwarting the 7/7 bombings in 2005."
Witness G replied: "I believe that proper assessments were made.
"I continue to judge there's no evidence or intelligence - an enormous amount of work has been done for both the Crevice plotters and the 7/7 plotters - to suggest they were or even aspirationally considering involvement in the Crevice plan in 2004."
The July 7 2005 bombings on three Tube trains and a bus carried out by Khan, Tanweer, Hasib Hussain, 18, and Jermaine Lindsay, 19, were the worst single terrorist atrocity on British soil.
As well as killing themselves and 52 others, the bombers injured more than 700 people.
The inquest at the Royal Courts of Justice in London was adjourned until tomorrow.Reuse content