In his early 20s, while living in Egypt, he thought deeply about converting to Islam. "What attracted me to it was that it seemed to provide a very complete way of life that made a lot of people very happy," he says.
After much thought he decided he could not commit to the demands of the religion. "I thought that if I was going to do it I would have to do it properly and pray five times a day," he says. "I know so many Muslims who drink alcohol and break the fast - nothing wrong with that, it's up to them - but if I were going to do it I would have to do it wholeheartedly. I didn't think that was going to be very compatible with my life."
Because of an attack made some two decades later in the name of Islam, Gardner will spend the rest of his life in a wheelchair - only occasionally rising to his full height with the aid of callipers. He was shot six times by a gang which greeted him in Arabic with the words "peace be upon you" before opening fire on him and killing his cameraman and friend Simon Cumbers.
His response to the shooting has been remarkable on so many levels. He has gratitude for his "good innings" as an able-bodied man, travelling the world, running marathons and teaching his children to Rollerblade. He retains a profound positivity, noting that technological innovations mean that his disability will not necessarily prevent future opportunities for pursuing his interest in such activities as paragliding and skiing, or reporting for the BBC.
Most admirable of all, perhaps, is his continued "respect" for a religion and culture in whose name he was so callously attacked, while preparing a report on the terror threat to Saudi oil installations. In 2006 he will sit on the board of the Festival of Muslim Cultures, a series of events across Britain. "I'm all for promoting more positive aspects of Islamic culture," he says.
This respect is tempered, though, by his deep understanding and wariness of the effects of the politicisation of Islam in recent decades. He will outline his knowledge of this subject in a 60-minute documentary for Radio 4 this Thursday, the making of which, you suspect, has been a cathartic experience for Gardner.
While he probes the roots of political Islam by interviewing such figures as the leading Egyptian Muslim Brotherhood activist Kemal el-Helbawi and the Libyan intellectual turned Afghan jihadist Noman Benotman, he refuses to engage with the type of fanatics who support the kind of bloody attacks to which he and Simon Cumbers fell victim.
"I would not be interviewing anybody who had any sympathy with the people who killed Simon Cumbers or shot me. I've got no interest in talking to those kind of extremists because they are beyond the pale of discussion and negotiation," he says. "Everybody who I interviewed was appalled and full of condemnation for what happened to us."
His eloquent, even delivery is infused with a rare hint of anger, his voice rising slightly as he observes: "Essentially the attack on us was a racist attack. Had we been brown skinned they wouldn't have shot us. We were shot because of the colours of our skin."
A year and a half after the shooting, no one has been brought to justice. Saudi investigators have told Gardner, and he believes them, that all but one of his attackers have been killed in subsequent shoot-outs with the authorities. "There's one person who's been arrested who we have been told took part in the attack on us," he says. "He was very badly wounded and the Saudis, I understand, were trying to give him the best medical attention they could so they could bring him to justice and charge him with the murderous attack on us."
Gardner, one would expect, might be called as a witness in subsequent proceedings. He says that this is not something he would be prepared to do.
"I don't think so because I would not be able to positively identify this person anyhow. The attack happened so quickly I would not be able to say. You are talking here about sentencing somebody to death effectively, if you say 'Yes, that's the guy'. I could never be sure enough," he says. "What I do know is that under Saudi law even if relatives pardoned that person - even if my cameraman's relatives pardoned him - most likely the Saudi government would bring their own state charges against him for acts of armed terrorism. I don't want to second guess what they would do but I think they would push for the maximum penalty. They are very tough on terrorism now in Saudi."
Gardner, 44, who spent eight months in hospital and has undergone 12 operations following the attack, says that he is "satisfied that I now know everything I need to know" about what happened that day in June 2004.
He now accepts that the minders assigned to him and Cumbers by the Saudi Ministry of Information were not complicit in the attack. "I had always suspected that somebody had dobbed us into the militants, but in fact it wasn't that. It was the militants themselves that saw us. It was very bad luck that they were on their way to a terror summit and they happened to see us and decided to execute us," he says but nonetheless maintains that "I do think we were looked after incompetently by the Saudi authorities".
Gardner, who had reported countless times from Saudi before, had previously avoided the Ministry of Information "like the plague" because "they have a reputation for incompetence" and because interviewees are often intimidated by the presence of government minders. In this case, because the BBC pair were using bulky equipment for a satellite feed, they needed to go through official channels.
Gardner regrets it. "They completely miscalculated the risk to us. A single police car would have been enough to deter the gunmen who came for us. Since then we've never received one penny of compensation. We put our trust in them to look after us. They got us shot, the minders ran away and we've never had any compensation from a country that is absolutely awash with oil money," he says.
In spite of what happened to him, Gardner maintains that "the Middle East is a far safer place than most people over here imagine" and he nurtures a desire to return to the region, though not in the near future to Saudi itself.
"Pretty much the only dangerous thing is the driving. I wouldn't recommend the drive from Abu Dhabi to Dubai - it's pretty manic," he says. "But I've lived many times in the Middle East and felt generally far safer than I do in London. Mugging is almost unheard of and in cities like Cairo Egyptians will go to enormous lengths to help you. They will cross multi-lane highways to help you repair a puncture. My affection for the Arab world is not born out of any political consideration whatsoever. It entirely comes out of my personal experience of the human kindness and hospitality."
Gardner does not extend this positive appraisal to Iraq, where Guardian correspondent Rory Carroll was recently kidnapped. The Independent's Robert Fisk recently suggested that the risks faced by reporters in trying to cover stories independently in Iraq were becoming too high.
"Fisk certainly knows what he's talking about. He's somebody who has twice interviewed Bin Laden and gone to places that most Western journalists would never dare go to in Lebanon," says Gardner. "The stakes have changed dramatically in the past year or so. Until last year, journalists operating in Iraq and other countries like Afghanistan took a calculated risk in going there. Yes, there was a chance, if they were unlucky, of being caught up in a car bombing or some kind of incident but they weren't being targeted as Western journalists.
"That's changed with the kidnapping of a number of journalists by extremist groups. The idea that journalists are simply there as neutral observers to report things is no longer accepted by the extremist groups in Iraq, who view them as somehow complicit in the occupation itself. There's a universal fear among all Western journalists out in Iraq that if they spend too long out in the street they will get grabbed probably by conventional criminal gangs who will try to sell them on to an Islamist group and they will end up getting their heads sawn off."
The difficulties in reporting are a source of great regret to Gardner, who can remember when correspondents in Baghdad could find time to visit the fish restaurants on the banks of the Tigris. "Of course it was painful to see the deprivation that Iraqis were suffering under sanctions and under Saddam, but you could have a pretty interesting time," he says. "That has changed. Western journalists are effectively prisoners of their own hotels and compounds. The attack against the Palestine and Sheraton hotels was pretty scary and could have been even worse had they got through the concrete barriers."
The son of diplomats, Gardner spent part of his childhood in Holland before being sent to Marlborough as a boarder, where he was captain of the shooting team but, by his own admission, not a star pupil academically. As a child he visited the Chelsea home of the writer and explorer Wilfred Thesiger, author of the classic travel books Arabian Sands and The Marsh Arabs, an experience that aroused his curiosity for the Middle East.
At school his English teacher encouraged him to take Islamic studies as an extra subject. "He had spent a lot of time in Iran and enthused us with an interest in Islamic architecture and culture. We learned the tenets of the five pillars of Islam."
As a student at Exeter University he took Arabic and Islamic Studies and went to live with a family in Egypt, becoming fluent in Arabic and developing his love for the culture.
He is not, however, "starry-eyed" about Islam, he makes clear.
After graduating he drifted into a career in finance, becoming a high-rolling Gulf-based investment banker with a villa, a swimming pool and a Mustang soft-top convertible. Ultimately, the life was not for him and, having previously written articles for newspapers and magazines he trained as journalist before setting up a bureau in Dubai and establishing himself as one of the BBC's best-known correspondents.
He says that some Western coverage of political Islam is "irresponsible" (citing early mistaken reports blaming the Oklahoma City bombings on Islamists) but points out: "There's a limit to how much you can blame the Western media when organisations like Hamas release videos of people clutching the Koran in one hand and a Kalashnikov in the other. And when al-Qa'ida couches every threat and every act of violence in Islamic terminology it's inevitable that some people are going to make some associations."
Similarly in Britain, he hears complaints from Muslim friends over the British press's obsession with certain extremists but thinks a degree of coverage is legitimate. "Sometimes the media are criticised for paying too much attention to extremists such as (radical group) Al-Muhajiroun. Muslims rightly point out that these people are not representative but that doesn't mean to say that their ideas are not violent and confrontational," he says.
Gardner was accused, ahead of the London bombings, of scaremongering over the potential for terror attacks. "One columnist took a swipe at me a couple of years ago and called me the BBC's insecurity correspondent, which I thought was quite funny, saying I was just trying to alarm people," he says. "But from the moment the Madrid bombs went off in March 2004 everybody who follows this grisly subject knew that it was only a matter of time before London got hit as well."
He doesn't subscribe to the theory put forward in Adam Curtis's award-winning BBC series The Power of Nightmares, suggesting that politicians were exploiting the public fear of terror attacks. "That was an immensely watchable and entertaining programme but it was also quite dangerous in the sense that it lulled people into a false sense of security," says Gardner. "The threat to me was always real. It's still real and hasn't evaporated. There's still a threat out there because of the way that Britain is perceived in the more extremist fringes of the Islamic world."
Gardner observes: "Although all the people we've interviewed for this (Radio 4) programme would describe themselves as non-violent, almost every Muslim we spoke to was critical of British policy in the Middle East and in the so-called 'war on terror'. While most people are just critical of it, inevitably there will be some who will be tempted to take that further."
The BBC security correspondent accepts now that it's not practical for him to be doing the reporting he previously excelled at, "hopping in and out of helicopters in places like Afghanistan or interviewing Yemenis in the backstreets".
But his depth of knowledge will not go wasted. "I think there's a big role for people like me to play in trying to explain the whole phenomenon of Islamic extremism - and of other things in the Middle East that are nothing to do with violence - to a Western public. The Middle East is a very misunderstood area and unfortunately a part of the world where the bad news tends to float to the top."
The BBC correspondent admires the way that Al Jazeera has "proved their critics wrong" and says the planned Al Jazeera International service means "the competition should be worried".
Gardner, the late convert to journalism, has previously advised those mulling over a similar career path to follow their dream. But asked what he would say to would-be war correspondents, his response is more rounded.
"It can be a lot of fun and terribly glamorous and exciting for the person who's out there doing the reporting. It's not a lot of fun for the person who's left behind, be it your mother, father, siblings or your spouse, your boyfriend or girlfriend," says Gardner, a father of two, who apologised to his parents for being on a drip when they visited him in hospital after the shooting.
"If you are leaving behind somebody who loves you and you are going to a dangerous place, I think a lot of us tend to forget that it's absolute hell we are putting them through. Being a foreign correspondent can be a selfless and a selfish profession. You are often taking a risk to get the real story but it's often at the expense of a lot of relationships. Foreign news is littered with the corpses of broken relationships and divorces."
Frank Gardner OBE's simple advice to those reporters who consider heading to the world's hotspots comes down to three words: "Know the risks."
'Koran and Country: How Islam Got Political' is on Thursday at 8pm on BBC Radio 4