The bomb plotter with a teddy bear collection

With his dyed red hair, pierced eyebrows and avowed interest in hardcore dance music, Andrew "Andy" Ibrahim was the epitome of the modern teenager. On his MySpace page, he described his interests as singing in a band, "hanging out", watching chat shows and "lots of reality TV".

There was little reason to expect the bright but gawky young man from a well-heeled suburb of Bristol to stand out from his peers. His English mother, a university administrator, and his Egyptian-born father, Nassif, a consultant pathologist, had ensured their son and his elder brother, Peter, spent their childhood in a settled and privileged environment.

When not living in the £800,000 family home in the commuter village of Frenchay, Andrew was sent to a series of private schools including Downside, the select Catholic public school near Bath whose former pupils include Auberon Waugh, Rocco Forte and Barclays Bank chief executive John Varley.

But beneath the veneer of an expensive education and efforts to strike a pose as a follower of popular culture, there was a disturbed and isolated young man whose adolescent search for identity and slow slide into a drug addiction became twisted into alternative persona - that of a would-be suicide bomber intent on mass murder in a crowded shopping centre.

A jury at Winchester Crown Court decided today that Ibrahim, who within a year of appearing on his MySpace page as a thoroughly Western youth had adopted the beard and garb of a strictly observant Muslim, was entirely serious in his preparations for an attack, which included producing a powerful homemade explosive and making himself three different sizes of suicide vest. The claims of his defence lawyer that he was not a bomber but a "prat" playing out the role of a fundamentalist were rejected out of hand.

Unlike the perpetrators of the 7/7 attacks in 2005 or several subsequent attempts to kill scores of people in Britain, Ibrahim had no links with Pakistan or a track record of training trips to al-Qa'ida camps. Instead, he fitted into an emerging sub-section of self-taught and rapidly self-radicalised "clean skins" who are nearly impossible to trace.

In less than three months, Andy Ibrahim, the teetotal public schoolboy who dyed his hair to look like the lead singer of American rock band Linkin Park and one glued his own pubic hair to his chin in class in homage to his favourite television programme, South Park, had become Isa Ibrahim, a chemistry student struggling with a crack and heroin habit whose Internet-based researches into Islam had led him to believe suicide bombing was justified and Britain was the "inside of a dirty toilet" - a phrase borrowed from the cyberspace preachings of fundamentalist preacher Abu Hamza.

Among the dozens of items downloaded by Ibrahim was the living will speech made by Mohammad Sidique Khan, the leader of the 7/7 bombings, in which he said: "Our words are dead until we give them life with our blood."

Underpinning this fascination with extremism and explosives was - perversely - a desire for admiration.

He told his trial that he was attracted by the "controversial" nature of the material he sought: "They made me feel a bit cooler. I didn't have friends or a social life but by looking at these files it made me feel a bit cooler. I didn't have friends or a social life but by looking at these files it made me feel a bit cooler. If felt not so sad, [not] such a loser. It made me feel better and bigger and a cooler person."

If it were not the observation and diligence of a fellow Muslim, who called police after noticing injuries caused to Ibrahim's feet and hands during a test explosion, it is likely that the potential bomber may have been able to bring his plan to fruition. Sitting inside a family assortment biscuit in his fridge was a quantity of a powerful explosive, hexamethylene triperoxide diamine or HMTD which Ibrahim had "cooked" in his home with ingredients including a packet of firelighters.

A counter-terrorism source said: "His preparations were detailed and as far as he was concerned he had all the equipment he needed to go out one day and murder as many people as he could. Certainly he was below the radar. A guy sitting at home alone in front of a computer screen is always going to be more difficult to spot than someone with known associates and links to training areas. We were certainly grateful for the phone call when it came."

When police swooped on Ibrahim's flat in another Bristol suburb, Westbury-on-Trym, on 17 April last year, they found a computer used extensively to download fundamentalist videos and guides on how to manufacture explosives from domestic ingredients such as bleach.

On his book shelves were 66 tomes ranging from Richard Dawkins's The God Delusion and a Jeffrey Archer novel to anti-western tracts and a work by Sayyid Qutb, the Egyptian theologian whose purist view of Islam influenced the development of Al Qaeda.

It was a very different trajectory from the one intended for Ibrahim, whose brother is a graduate from Jesus College, Oxford, and works as a software engineer. His father, a consultant histopathologist or specialist in human tissue, is a leading authority on cancer cells.

But the self-declared "lost sheep" of his family was clearly a troubled individual. He was expelled from three schools for taking drugs and inappropriate behaviour, including one incident when he was asked to leave a £9,000-a-term academy for smacking female classmates on the bottom.

At the age of 16, Ibrahim's previously secure family life was upended by the divorce of his parents, an event for which he told the court he blamed himself. It was at around this point that the teenager's dabbling in drugs spiralled downwards into full-blown addiction.

He progressed from cannabis to ecstasy to the horse tranquilliser ketamine before becoming hooked on heroin and crack with a £60-a-day habit. Ibrahim told the court: "Cannabis was not enough, I wanted to get the most extreme drugs I could, I wanted to be different from others."

After being asked to leave his mother's home because of his addiction, Ibrahim took up residence in a Bristol hostel in January 2007, stealing and selling the Big Issue magazine while trying to cope with his cravings. The court heard that he believed his parents had "disowned" him.

One of the mechanisms he found to "distract" himself was his growing interest and belief in Islam, visiting a local mosque several times a day. He said: "The desire was nowhere near as great as it was because I was so distracted. I didn't have time to think about drugs."

By February 2008, the Islamist alter ego developed by Ibrahim had come to dominate his life. He changed his named by deed poll and told friends that he believed the 9/11 attacks were "a justified response" to Western foreign policy while openly carrying around instructions at college on the ingredients needed to make explosives.

According to prosecutors, the desire to turn theory into practice took hold early in April last year, when Ibrahim began to reconnoitre his target - the Broadmead shopping centre in Bristol, where he spent 60 minutes one day without entering any of its 100 shops and noting the location of bins, lifts, escalators and exits as well as describing the food court as a "dense area".

Two days later, he began the process of allegedly assembling a device, visiting a branch of Boots in the same shopping centre to buy hydrogen peroxide bleach, another ingredient for HMTD, and buying a number of electrical goods from the Maplins chain in Bristol to fashion a crude detonation circuit later found by police under his kitchen sink.

Ibrahim, who refused to discuss any of allegations against him during 11 hours of police interviews, insisted by way of explanation that his actions were those of a social inadequate who inhabited a world of fantasy.

In one extraordinary courtroom revelation, the self-styled mujahid revealed that he still had a collection of nine teddy bears, one of which, Mr Fox, was a favourite with which he identified.

Describing the cuddly toy, Ibrahim said: "He's quite mischievous, he's not well-behaved, he is rude. He picks on the other bears and he is rude to them... He plays tricks on people, he would hit other people. Hit the other bears."

It is possible that in this, the jurors saw a description of Ibrahim's own personality - a young man who believed he had found his purpose in "hitting" others with high explosive.