I was halfway through climbing into a taxi, due to take myself and Christopher Hitchens from Oxford to Heathrow, when the man himself stopped me mid-clamber with an urgent, ‘Hang on.’ I turned to see the 61-year-old journalist and polemicist standing in the middle of the pavement on the High Street, casually lighting a cigarette. At the time, this was something of a surprise to see, as although he is almost as famous for his legendarily unending appetite for tobacco and alcohol as he is for his fierce eloquence in his essays and debates, I was sure I’d read somewhere that he had finally kicked the lifelong habit. With this in mind, I decided to confront him, announcing in my most accusatory voice, ‘I thought you’d quit.’ Disappointingly, he appeared utterly unfazed at having been caught in the act. Instead, he merely took a long and evidently soothing drag of nicotine, before replying in that unmistakably mellifluous and well-spoken voice, ‘I have.’ He smiled before letting the smoke curl slowly from his lips.

Just days after this exchange, Hitchens made the following, uncharacteristically brief announcement in Vanity Fair, where he has been a Contributing Editor since 1992: ‘I have been advised by my physician that I must undergo a course of chemotherapy on my esophagus. This advice seems persuasive to me. I regret having had to cancel so many engagements at such short notice.’ Many critics were quick to point out that the disease seemed to have been self-inflicted, though Hitchens was first to acknolwedge this: ‘I have been taunting the Reaper into taking a free scythe in my direction and have now succumbed to something so predictable and banal that it bores even me. Rage would be beside the point for the same reason.’

In the intervening months, the treatment he has undertaken has left him bald, more reflective and noticeably thinner. With this in mind, and considering the severity of his type of cancer, one would be forgiven for expecting the huge number of public appearances and regular essays that he has maintained over the years to slow down somewhat. In fact, quite the opposite is true. Since his diagnosis, Hitchens has been difficult to avoid; he continues his written columns, has been the subject of numerous interviews, and even debated with Tony Blair over religion. Perhaps such energy and activity is equally predictable in its way. Given the fact that he has described chemotherapy as leaving him feeling ‘swamped with passivity and impotence: dissolving in powerlessness like a sugar lump in water’, it is at the very least an understandable response.

It was his public debate with Blair in late November last year that showed just how much Hitchens has exploded into the public eye. Mention his name only a year ago, and more often than not, you’d get a slack-jawed shrug of non-recognition; now, following that debate (Blair’s first since leaving Downing Street) and an extended Newsnight interview with Paxman, everyone seems to be aware of him. And a good thing it is too. When discussing what he knows about, it is difficult to overstate the depth of knowledge Hitchens displays and the convincingness of his arguments, while his style, both when speaking and writing, is one of unfailing eloquence. His vocabulary is astonishingly diverse and, it seems, inexhaustible, yet is often followed by a healthy measure of abrupt, unfiltered scorn, all the more effective for its bluntness. His targets are also impressively diverse, from condemning Ronald Reagan as ‘a cruel and stupid lizard’, to describing Mother Teresa as a ‘thieving Albanian dwarf’. As Richard Dawkins has advised, ‘If you are… invited to debate with Christopher Hitchens, decline.’

More significantly, his long career as a journalist has always had the pleasing aura of integrity surrounding it. Though his popularity with his comrades on the Left waned dramatically following his fervent and continuing support of the invasion of Iraq, it is difficult to fault his commitment to any cause. His support of the deposition of Saddam had its roots in his first-hand experiences in Iraq and Kuwait, while he has visited all three countries in the so-called ‘Axis of Evil’ – Iraq, Iran and North Korea – in order to ensure his opinions on world politics are as well informed as possible. When I brought this up, one could detect a certain note of pride in his voice as he nodded in agreement: ‘Well, I’m the only one to have done that. I’m the only writer, at any rate, to go to North Korea, Iran and Iraq. I’m sure I’d know if there was another one. And I don’t think there would be a diplomat who would have had all three postings because they’re not very congruent. Probably some arms dealer or terrorist has managed to do all three.’

In 2007, the publication of his best-selling anti-religion book, god Is Not Great (a very deliberately punctuated title) gave his profile a significant boost. I asked him about this increase in fame, and he shifted in his seat uncomfortably in response. After glancing out of the window at the departing Oxfordshire countryside, he turned to meet my gaze. ‘Perhaps it seems as if I’m on [TV] more than I am… The reason I don’t do it very much is that it does become a problem, and I’ve known people to whom it’s happened. That’s what you are, a talking head, paid to have opinions, and therefore you’ll have them on whatever they ask you about. You become a TV personality.’ He then paused for a swig of bottled water (9am is perhaps too early for whiskey, even for Hitchens), before admitting, ‘I’ve actually been offered a show, but I know I don’t want to do one… You can end up feigning not just to know, but to care. So gradually you do become a complete phoney with pretended outrage.’

This impulse to resist knee-jerk reactions and uninformed opinions can be seen in his noticeable reticence about high-profile issues such as climate change and US healthcare. I asked him about this tendency to hold back on such issues, and he agreed that he is always repulsed by uninformed opinion. ‘I’m not very knowledgeable about health insurance. So where I don’t consider myself to be very well informed, or perhaps have something very interesting to say, I don’t speak. I’ve actually said on the air sometimes, ‘Well actually, I don’t really know about that,’ or, ‘I don’t have an opinion.’ It always completely exasperates them: ‘So why do we invite you on then?’ ‘Well, I know most of your guests would rather die than say this, but where you’re not sure what you’re talking about, you’re well advised to shut the fuck up.’

It’s clear from this how protective he is of the English language, and has little time for its waste or misuse. He also reserves similar disdain for the state of the arts and the media today, and proudly divulged that he rarely watches television: ‘It has to be a real crisis if I’m prepared to turn it on. It’s way down the other end of the house. I might not even have one if it wasn’t for DVDs.’ Films are avoided in a similar manner, as Hitchens lamented how they’re no longer made for people like him. ‘I’m the wrong demographic, as they say. I’m the wrong age, for one thing. Most films are made to formulae for people much younger than me. And then I think most films depend for their sense of humour upon things that I don’t find particularly funny. And most films are vehicles for individual stars. And most of them don’t care at all about suspension of disbelief, so they’ll irritate you quite early on by making a character do something suicidally implausible. At which point it spoils the thing, and I think, ‘Well, no, he wouldn’t have done that, don’t be stupid.’ It’s just a shortcut to make it work. I can’t remember the last time I went to the cinema without feeling insulted or annoyed.’ Believing this rather unexpected rant to be over, I cautiously began another question before being immediately interrupted by a loud exclamation: ‘Avatar! I couldn’t believe it…’ For once, he seemed lost for words. ‘Sometimes I don’t get things at all, and I think, ‘Well, maybe I’m becoming a curmudgeon.’ It’s… the Barry Manilow effect – when you see Barry Manilow and you think, ‘There are people who want to hear this, and they want more of it.’ Clearly there’s something I’ve missed.’

Indeed, it is a plausible suggestion that Christopher Hitchens might be gradually losing his relevance. His most recent articles include two levelled against Henry Kissinger (an old foe), and one on how to make the perfect cup of tea. Not exactly cutting edge stuff. Certainly, many interviewers (including Paxman) have treated him in an almost condescendingly friendly way, as if it would be unreasonable to expect the once formidable intellectual spark from a cancer sufferer now eligible for a bus pass. However, this attitude of lenience is both grossly unfair and utterly patronising towards a man whose mind is still vibrantly engaged, even if his body is rapidly failing him.

As the taxi pulled up at Heathrow and we strolled towards the entrance, I recalled reading that Nick Clegg had once been an intern for Hitchens when he worked at The Nation. With the Coalition Government at this point still young, I was keen to find out his opinions about the man, but the disappointing response was merely, ‘I don’t remember him very well.’ He paused to light up another cigarette before heading for his flight, and as he did so, remarked in an off-hand manner, ‘I remember better Eddy Miliband, who was also there. I took more notice of him.’ At this point, the Labour leadership contest had barely begun, but Hitchens seemed certain that the younger Miliband was destined for great things. I disagreed, confident that David would be the triumphant brother. I had little notion that, just a few months later, Hitchen’s instincts would prove correct once again. It is clear that, though it is most likely self-inflicted, his deadly ailment is cutting down an intellect still furiously alive and in its prime. The world and the English language will be far duller in his absence.