During our first two months in Jeddah, Faye and I relished our new and luxurious lifestyle: a shiny jeep, two swimming pools, domestic help, and a tax-free salary. The luxury of living in a modern city with a developed infrastructure cocooned me from the frightful reality of life in Saudi Arabia.

My goatee beard and good Arabic ensured that I could pass for an Arab.

But looking like a young Saudi was not enough: I had to act Saudi, be Saudi. And here I failed.

My first clash with Saudi culture came when, being driven around in a bulletproof jeep, I saw African women in black abayas tending to the rubbish bins outside restaurants, residences and other busy places.

“Why are there so many black cleaners on the streets?” I asked the driver. The driver laughed. “They’re not cleaners. They are scavengers; women who collect cardboard from all across Jeddah and then sell it. They also collect bottles, drink cans, bags.”

“You don’t find it objectionable that poor immigrant women work in such undignified and unhygienic conditions on the streets?”

“Believe me, there are worse jobs women can do.”

Though it grieves me to admit it, the driver was right. In Saudi Arabia women indeed did do worse jobs. Many of the African women lived in an area of Jeddah known as Karantina, a slum full of poverty, prostitution and disease.

A visit to Karantina, a perversion of the term “quarantine”, was one of the worst of my life. Thousands of people who had been living in Saudi Arabia for decades, but without passports, had been deemed “illegal” by the government and, quite literally, abandoned under a flyover.

A non-Saudi black student I had met at the British Council accompanied me. “Last week a woman gave birth here,” he said, pointing to a ramshackle cardboard shanty. Disturbed, I now realised that the materials I had seen those women carrying were not always for sale but for shelter.

I had never expected to see such naked poverty in Saudi Arabia.

At that moment it dawned on me that Britain, my home, had given refuge to thousands of black Africans from Somalia and Sudan: I had seen them in their droves in Whitechapel. They prayed, had their own mosques, were free and were given government housing.

Many Muslims enjoyed a better lifestyle in non-Muslim Britain than they did in Muslim Saudi Arabia. At that moment I longed to be home again.

All my talk of ummah seemed so juvenile now. It was only in the comfort of Britain that Islamists could come out with such radical utopian slogans as one government, one ever expanding country, for one Muslim nation. The racist reality of the Arab psyche would never accept black and white people as equal.

Standing in Karantina that day, I reminisced and marvelled over what I previously considered as wrong: mixed-race, mixed-religion marriages. The students to whom I described life in modern multi-ethnic Britain could not comprehend that such a world of freedom, away from “normal” Saudi racism, could exist.

Racism was an integral part of Saudi society. My students often used the word “nigger” to describe black people. Even dark-skinned Arabs were considered inferior to their lighter-skinned cousins. I was living in the world’s most avowedly Muslim country, yet I found it anything but. I was appalled by the imposition of Wahhabism in the public realm, something I had implicitly sought as an Islamist.

Part of this local culture consisted of public institutions being segregated and women banned from driving on the grounds that it would give rise to “licentiousness”. I was repeatedly astounded at the stares Faye got from Saudi men and I from Saudi women.

Faye was not immodest in her dress. Out of respect for local custom, she wore the long black abaya and covered her hair in a black scarf. In all the years I had known my wife, never had I seen her appear so dull. Yet on two occasions she was accosted by passing Saudi youths from their cars. On another occasion a man pulled up beside our car and offered her his phone number.

In supermarkets I only had to be away from Faye for five minutes and Saudi men would hiss or whisper obscenities as they walked past. When Faye discussed her experiences with local women at the British Council they said: “Welcome to Saudi Arabia.”

After a month in Jeddah I heard from an Asian taxi driver about a Filipino worker who had brought his new bride to live with him in Jeddah. After visiting the Balad shopping district the couple caught a taxi home. Some way through their journey the Saudi driver complained that the car was not working properly and perhaps the man could help push it. The passenger obliged. Within seconds the Saudi driver had sped off with the man’s wife in his car and, months later, there was still no clue as to her whereabouts.

We had heard stories of the abduction of women from taxis by sex-deprived Saudi youths. At a Saudi friend’s wedding at a luxurious hotel in Jeddah, women dared not step out of their hotel rooms and walk to the banqueting hall for fear of abduction by the bodyguards of a Saudi prince who also happened to be staying there.

Why had the veil and segregation not prevented such behaviour? My Saudi acquaintances, many of them university graduates, argued strongly that, on the contrary, it was the veil and other social norms that were responsible for such widespread sexual frustration among Saudi youth.

At work the British Council introduced free internet access for educational purposes. Within days the students had downloaded the most obscene pornography from sites banned in Saudi Arabia, but easily accessed via the British Council’s satellite connection. Segregation of the sexes, made worse by the veil, had spawned a culture of pent-up sexual frustration that expressed itself in the unhealthiest ways.

Using Bluetooth technology on mobile phones, strangers sent pornographic clips to one another. Many of the clips were recordings of homosexual acts between Saudis and many featured young Saudis in orgies in Lebanon and Egypt. The obsession with sex in Saudi Arabia had reached worrying levels: rape and abuse of both sexes occurred frequently, some cases even reaching the usually censored national press.

My students told me about the day in March 2002 when the Muttawa [the religious police] had forbidden firefighters in Mecca from entering a blazing school building because the girls inside were not wearing veils. Consequently 15 young women burnt to death, but Wahhabism held its head high, claiming that God’s law had been maintained.

As a young Islamist, I organised events at college and in the local community that were strictly segregated and I believed in it. Living in Saudi Arabia, I could see the logical outcome of such segregation.

In my Islamist days we relished stating that Aids and other sexually transmitted diseases were the result of the moral degeneracy of the West. Large numbers of Islamists in Britain hounded prostitutes in Brick Lane and flippantly quoted divorce and abortion rates in Britain. The implication was that Muslim morality was superior. Now, more than ever, I was convinced that this too was Islamist propaganda, designed to undermine the West and inject false confidence in Muslim minds.

I worried whether my observations were idiosyncratic, the musings of a wandering mind. I discussed my troubles with other British Muslims working at the British Council. Jamal, who was of a Wahhabi bent, fully agreed with what I observed and went further. “Ed, my wife wore the veil back home in Britain and even there she did not get as many stares as she gets when we go out here.” Another British Muslim had gone as far as tinting his car windows black in order to prevent young Saudis gaping at his wife.

The problems of Saudi Arabia were not limited to racism and sexual frustration.

In contemporary Wahhabism there are two broad factions. One is publicly supportive of the House of Saud, and will endorse any policy decision reached by the Saudi government and provide scriptural justification for it. The second believes that the House of Saud should be forcibly removed and the Wahhabi clerics take charge. Osama Bin Laden and Al-Qaeda are from the second school.

In Mecca, Medina and Jeddah I met young men with angry faces from Europe, students at various Wahhabi seminaries. They reminded me of my extremist days.

They were candid in discussing their frustrations with Saudi Arabia. The country was not sufficiently Islamic; it had strayed from the teachings of Wahhabism. They were firmly on the side of the monarchy and the clerics who supported it. Soon they were to return to the West, well versed in Arabic, fully indoctrinated by Wahhabism, to become imams in British mosques.

By the summer of 2005 Faye and I had only eight weeks left in Saudi Arabia before we would return home to London. Thursday, July 7, was the beginning of the Saudi weekend. Faye and I were due to lunch with Sultan, a Saudi banker who was financial adviser to four government ministers. I wanted to gauge what he and his wife, Faye’s student, thought about life inside the land of their birth.

On television that morning we watched the developing story of a power cut on the London Underground. As the cameras focused on King’s Cross, Edgware Road, Aldgate and Russell Square, I looked on with a mixture of interest and homesickness. Soon the power-cut story turned into shell-shocked reportage of a series of terrorist bombings.

My initial suspicion was that the perpetrators were Saudis. My experience of them, their virulence towards my non-Muslim friends, their hate-filled textbooks, made me think that Bin Laden’s Saudi soldiers had now targeted my home town. It never crossed my mind that the rhetoric of jihad introduced to Britain by Hizb ut-Tahrir could have anything to do with such horror.

My sister avoided the suicide attack on Aldgate station by four minutes. On the previous day London had won the Olympic bid. At the British Council we had celebrated along with the nation that was now in mourning.

The G8 summit in Scotland had also been derailed by events further south. The summit, thanks largely to the combined efforts of Tony Blair and Bob Geldof, had been set to tackle poverty in Africa. Now it was forced to address Islamist terrorism; Arab grievances had hijacked the agenda again.

The fact that hundreds of children die in Africa every day would be of no relevance to a committed Islamist. In the extremist mind the plight of the tiny Palestinian nation is more important than the deaths of millions of black Africans. Let them die, they’re not Muslims, would be the unspoken line of argument. As an Islamist it was only the suffering of Muslims that had moved me. Now human suffering mattered to me, regardless of religion.

Faye and I were glued to the television for hours. Watching fellow Londoners come out of Tube stations injured and mortified, but facing the world with a defiant sense of dignity, made me feel proud to be British.

We met Sultan and his wife at an Indian restaurant near the British Council. Sultan was in his early thirties and his wife in her late twenties. They had travelled widely and seemed much more liberal than most Saudis I had met. Behind a makeshift partition, the restaurant surroundings were considered private and his wife, to my amazement, removed her veil.

We discussed our travels.

Sultan spoke fondly of his time in London, particularly his placement at Coutts as a trainee banker. We then moved on to the subject uppermost in my mind, the terrorist attacks on London. My host did not really seem to care. He expressed no real sympathy or shock, despite speaking so warmly of his time in London.

“I suppose they will say Bin Laden was behind the attacks. They blamed us for 9/11,” he said.

Keen to take him up on his comment, I asked him: “Based on your education in Saudi Arabian schools, do you think there is a connection between the form of Islam children are taught here and the action of 15 Saudi men on September 11?”

Without thinking, his immediate response was, ‘No. No, because Saudis were not behind 9/11. The plane hijackers were not Saudi men. One thousand two hundred and forty-six Jews were absent from work on that day and there is the proof that they, the Jews, were behind the killings. Not Saudis.”

It was the first time I heard so precise a number of Jewish absentees. I sat there pondering on the pan-Arab denial of the truth, a refusal to accept that the Wahhabi jihadi terrorism festering in their midst had inflicted calamities on the entire world.

In my class the following Sunday, the beginning of the Saudi working week, were nearly 60 Saudis. Only one mentioned the London bombings.

“Was your family harmed?” he asked.

“My sister missed an explosion by four minutes but otherwise they’re all fine, thank you.”

The student, before a full class, sighed and said: “There are no benefits in terrorism. Why do people kill innocents?”

Two others quickly gave him his answer in Arabic: “There are benefits. They will feel how we feel.”

I was livid. “Excuse me?” I said. “Who will know how it feels?”

“We don’t mean you, teacher,” said one. “We are talking about people in England. You are here. They need to know how Iraqis and Palestinians feel.”

“The British people have been bombed by the IRA for years,” I retorted. “Londoners were bombed by Hitler during the blitz. The largest demonstrations against the war in Iraq were in London. People in Britain don’t need to be taught what it feels like to be bombed.”

Several students nodded in agreement. The argumentative ones became quiet. Were they convinced by what I had said? It was difficult to tell.

Two weeks after the terrorist attacks in London another Saudi student raised his hand and asked: “Teacher, how can I go to London?”

“Much depends on your reason for going to Britain. Do you want to study or just be a tourist?”

“Teacher, I want to go London next month. I want bomb, big bomb in London, again. I want make jihad!”

“What?” I exclaimed. Another student raised both hands and shouted: “Me too! Me too!”

Other students applauded those who had just articulated what many of them were thinking. I was incandescent. In protest I walked out of the classroom to a chorus of jeering and catcalls.

My time in Saudi Arabia bolstered my conviction that an austere form of Islam (Wahhabism) married to a politicised Islam (Islamism) is wreaking havoc in the world. This anger-ridden ideology, an ideology I once advocated, is not only a threat to Islam and Muslims, but to the entire civilised world.

I vowed, in my own limited way, to fight those who had hijacked my faith, defamed my prophet and killed thousands of my own people: the human race. I was encouraged when Tony Blair announced on August 5, 2005, plans to proscribe an array of Islamist organisations that operated in Britain, foremost among them Hizb ut-Tahrir.

At the time I was impressed by Blair’s resolve. The Hizb should have been outlawed a decade ago and so spared many of us so much misery. Sadly the legislation was shelved last year amid fears that a ban would only add to the group’s attraction, so it remains both legal and active today. But it is not too late.