Economic deprivation, social exclusion and family breakdown are often cited as the underlying reasons for why increasing numbers of young British Muslim men are driven into religious extremism.

But for Omar Khyam, 25, the ringleader of the fertiliser bomb plot, terrorism appears almost to have been a career choice.

The grandson of a British Army colonel and the son of a wealthy businessman, he enjoyed a comfortable middle class childhood in a secular household in Crawley.

Like many British schoolboys, he loved those twin pillars of English life - Manchester United and fish and chips.

Although his parents were divorced, he was still part of a close family, studied hard at school and was mad about cricket - a sport at which he excelled. According to some, he dreamed of playing for Sussex, or even England.

The idea of Khyam walking out in cricket whites at Lords seems extraordinary now.

Instead of playing for his country, he stands convicted of plotting to bomb it.

The story of his radicalisation is a cautionary tale because it proves that even in the absence of poverty, social isolation and the influence of a malign peer group, religious extremism, death and destruction can still seem like an attractive option for a young middle class British Muslim in modern Britain.

Khyam's family claim he was "brainwashed" at an impressionable age by religious extremists. Undoubtedly this played its part.

What is known is that Khyam became interested in radical Islam at an exceptionally young age - several years before the conflicts in Afghanistan and Iraq that are blamed for inspiring the post 9/11 generation of terrorists.

Khyam was just 22 at the time of his arrest in March 2004 and was already in the final stages of preparing a major al Qaida-inspired attack.

Compare that to Mohammed Sidique Khan, the ringleader of the July 7 suicide cell, who was 30 when he blew himself up on the London Underground.

In one of the pair's secretly-taped conversations, Khan once told the young Khyam: "There is no one higher than you."

How did Khyam rise so quickly to become the leader of a terror plot designed to kill innocent British civilians in nightclubs and shopping centres?

It is thought this transformation began when he was aged about 15.

At an age when most teenage boys are preoccupied with girlfriends, rock music and football, Khyam was instead becoming more and more interested in religion, particularly in "the freedom of Muslim lands from occupation", as he would later put it.

Until then, religion was something his family paid little attention to.

His grandfather had served in the British Army during the Second World War, moving to the UK in the 1970s.

Although they were Muslims, Khyam, whose family originated in Pakistan, grew up in a secular household with his mother and brothers in a tidy if unremarkable housing estate of post-war brick terraces on the edge of Crawley.

He attended Northgate Primary School in Northgate, Crawley then Hazelwick School in nearby Three Bridges.

He played football, was captain of the cricket team - he also played at club level and was captain of the Sussex under-18s cricket team - had many non-Muslim friends and performed reasonably well in his GCSEs.

After school, he went to study A-levels at East Surrey College - apparently with the aim of going on to study for a university degree.

But it was about this time that Khyam began to go off the rails.

He had started to take a keen interest in the trouble between India and Pakistan and, on a 1999 visit to the family homeland of Pakistan, he spoke to members of groups active in the disputed Kashmir territory about the independence movement.

Khyam had also been regularly worshipping at his local mosque and - without his family and friends being aware - he was attending meetings of the now-proscribed radical Islamic group al-Muhajiroun, led by the now-exiled extremist cleric Omar Bakri Mohammed.

At the age of 17 and while still at college, Khyam convinced his mother he was moving to France to continue his studies and left the family home. He even persuaded a friend to post a letter to her from France to keep up the pretence.

But in reality, he had run away to the hills of Pakistan to join a militant training camp.

The first the family knew was when he called them from Pakistan.

Khyam told his trial that, while at the camp, he learnt "everything I needed for guerrilla warfare in Kashmir", including weapons training in AK47s, pistols, rocket-propelled grenades (RPGs), and sniper rifles, climbing and crawling techniques and reconnaissance.

In March 2000, after three months there, members of his family - some of whom were in Pakistani military intelligence - managed to trace him. He travelled back down from the mountains and was reunited with his grandfather.

After returning to Crawley, Khyam would claim that most of his family were happy at what he had done, except his mother. As a consequence, he moved briefly to Belgium to help his father run his clothes shop business, before returning to the UK again and to East Surrey College.

But he failed to take his final exams and so in 2001, at the age of 20, he enrolled on a foundation course at the Metropolitan University in north London.

Before this began, he once again visited Pakistan for a friend's wedding.

While there, he crossed the border into Afghanistan to find out how the country worked under the Taliban. The increasingly radical and strictly religious Khyam was clearly impressed.

He said: "They were amazing people.

"They loved Allah very much. This is how an Islamic state should be."

Khyam said he found the Taliban were loved in Afghanistan and that Osama bin Laden, leader of the al Qaida terror network, was a hero. On his return to the UK, he began sending money and equipment to Afghanistan to help the cause.

Khyam's conversion to the doctrine of radical Islam was by now almost complete.

After the 9/11 attacks, he said he felt "happy" - despite the deaths of 3,000 people - because America was the "greatest enemy" of Islam.

After Khyam was arrested - while on honeymoon with his bride Saira Khan at a hotel in Crawley, three days after their marriage in a civil ceremony - his family claimed he had been "brainwashed".

Apparently laying the blame at the door of al-Muhajiroun and at those with whom Khyam had associated while in Pakistan, his uncle Sajjah Ahmad told how relatives wrestled him from the grip of fanatics after he fell under their spell.

He told a national newspaper: "Omar was a normal kid until al-Muhajiroun started preaching their hatred round here.

"They preyed on boys at the mosque and even in the shopping centres, getting them when they were young and impressionable.

"They showed them videos of the injustices Muslims were suffering and then channelled their anger into hatred.

"Then suddenly Omar disappeared. We didn't know where he had gone until he rang and said he was in Pakistan. So we used our contacts in the Pakistan army to find where he was and we went out to bring him back.

"When he came back, he was shocked at the commotion it had caused. He saw how angry the family were and settled down.

"He was a devout Muslim, but he was a normal kid who loved Manchester United and played football and cricket.

"He was brilliant and could have played for England, but he started to lose interest when he got involved with these extremists."

When the time came for Khyam to give evidence at his trial and to finally provide some kind of public explanation for his actions, he managed less than two days in the witness box before dramatically calling a halt to proceedings.

Khyam claimed that the Pakistani secret services had been in touch with his family and that he feared for their safety if he continued his testimony.