I can’t say I ever exactly warmed to his publically cultivated image: yet underneath the dandiacal shtick – which was time- as well as shop-worn – there lurked a sensitive, kind, tormented man. On top of addiction (itself a form of obsessive-compulsive disorder), Seb was riddled with the gamut of repetitive counting, hand-washing and magical thinking. He took smack because he was an addict, for sure, but I think he also used it to silence this psychic Babel.

He climbed on and off the wagon many of the rest of us managed to ride – but in this there was no disgrace. Less easy to take was the attitudinising – at least when you understand, as I believe I do to my marrow, that once someone has crossed the line, far from being a lifestyle choice (albeit of an arid and unprofitable kind) intoxication is nought save a pathology. I saw Seb as trapped inside a performance that he was powerless to give up – one that did for him in the end.

We joined the cortege at the top of Lower Regent Street and followed the horse-drawn hearse past Bates, the hatters. There was a representative sample of the existentialist inhabitants of the inner city: suited and booted sub-Goths twirling skull-topped canes, demi-whores in corsets with BDD (Breast Dismorphic Disorder). Stephen Fry offered me a large, soft, cool, moist hand and greetings, and then observed that we were unlikely to see the likes of such a funeral again in Soho. Unkindly, I suggested that he might prefer us to be dropping like gaudy flies, if spectacle was the object.

In fact, Stephen’s address to the mourners was measured, calm, only a little wry, and quite moving. He didn’t play to the gallery who look upon the likes of Sebastian Horsley as some kind of freak show. Seb was predeceased by a few weeks by Michael Wojas, ex-proprietor of the Colony Room, the private members club where he often hung out. I knew Michael back in the day, and used him – quite unashamedly – as the model for the barman, Hilary Edmonds, in my story Foie Humain from Liver.

As I said in the story, the real tragedy of these Soho denizens was not that they belonged to some kind of avant garde, but that the cultural revolution they spearheaded was carried forward without them: as outside in Old Compton Street everyone got gayer and happier, inside the Colony Room everyone got sadder and older. Wojas died of chronic alcoholism at 53, Horsley of a heroin overdose at 47. There’s no way you can paint up either death as anything but miserable and futile.

My tiny netbook had burnt out after I’d stupidly shut it while it was shutting down then left it to burn out its mother board. Or so Nomi, the guy in the local cyber-café-cum-phone-unlocking hangout, told me. He ordered a new mother board from Hong Kong to replace it, and when the job was done (160 shitters), we checked that it booted up and I tucked it away in my rucksack.

But on the train the keyboard obstinately refused to work at all; disaster: I had two pieces to file before I got beyond internet range in 36 hours. I called Toby the computer man: “Oh,” he said, “it sounds like this guy failed to reconnect the keyboard, it’s a simple enough job but you have to open the machine and obviously you need to know what you’re doing.”

Obviously I wouldn’t know what I was doing: I orbit the world of handiness in a space station of cackhandedness banged together out of old 2x4s and six-inch nails. Some years ago I reached the tipping point and had to acknowledge that I would probably never be able to put up a set of shelves or flambé a crème brûlée. I concur with Dr Johnson that to be unhandy is in itself a form of stupidity, and although I once – to please my wife – spent something like a fortnight installing a new toilet-roll holder (I did drilling and everything!), when she returned home from her holiday, she tartly observed that it was the wrong way round.

When I came off the phone and was sitting there gently weeping, the young man sitting in the seat behind me leant over and said, “I’m sorry, but I couldn’t help overhearing your conversation and I think I might be able to fix your computer.” Yes, bizarre – but true: a good computer Samaritan. A Phillips screwdriver was quickly obtained from the train guard and Alex (for this was his name) set to work. I couldn’t bear to look, given that manipulations like this seem like neurosurgery to me. Within what seemed to be a few minutes, Alex had done it and the world breathed a collective sigh of relief, safe in the knowledge that it would have another pretentious art catalogue essay by Will Self after all.

Alex wasn’t just a whizz at mending computers, he was also a soon-to-be-qualified psychiatric nurse who was thinking of going on to qualify in law so he could act as an advocate for mentally ill people. Moreover, he also grew all his vegetables on allotment near his home in Glasgow, and liked to go bare-bones backpacking around the Highlands. Indeed, rather like Bruno who took me down the London sewers a few weeks ago, he was one of those young men who seem to move lightly and efficiently around the world, and to me – who when young moved heavily and inefficiently around the world, trashing bits of it along the way – this seems far more of a miracle than a pathetic little netbook.

Which brings us to the sewers, which I descended into last evening in the charming company of Bruno Rinvolucri of Resonance FM. Bruno makes a habit of this sort of thing – and in one way it’s easy to see why: there is something INCREDIBLY strange about walking 40 feet below the surface of London in a huge shit-smeared culvert; but in another way, he has to be the most psycho geographer of us all. We started at Brixton Water Lane, where we descended into the culvert that the lost River Effra now runs in. This was a fairly stiff, near-knee-high current of dirty-dish-water-coloured fluid (it smelt of old dish water as well). After a few hundred yards we reached an inflow that made the slithery progress feel distinctly vertiginous; and shortly after that a chamber opened up to the right, and we descended another ladder into a deeper, wider-bore and drier sewer, which we followed all the way to Clapham North.

Stalactites of calcified toilet paper with ancient sanitary towels trapped in their convolutions slow-dripped from the ceiling; cars hammering over the manhole covers up above sent reverberations booming along the tube; our headtorches struck weird glissading light-pulses across the curved courses of stock bricks (which had remained paradoxically fresh and yellow in this “unpolluted” environment). The smell! Why didn’t they tell us: dish water, yes, braided with excrement – mephitic beyond noisome.

Bruno, who is as engaging as you would expect someone who has a passion for this sort of thing to be (ex-rickshaw driver, nascent physical anthropologist, favours rooms to let for £25, so if you have a queer space you need tenanted in the Oxford area get in touch), confessed towards the end of our 1.5 mile slosh that when he first began going down the sewers he found it pretty scary; furthermore that one or two of the people he’d brought down for his Resonance recordings had also freaked out. Then there came a terrible noise like a giant burp or fart-afflatus from the murk up ahead, where the tunnel widened into a high-colonic cathedral. Bruno explained that if we continued down this gently sloping chamber of shiterrors it would begin “to look as if there were a wall of water ahead of us … ” and it was out of this that these great eggy burps were coming.

“Actually,” Bruno vouchsafed as we began to inch our way back up to the surface, like Wellsian Morlocks in denim, “when you smell the rotten eggs it’s probably time to get out.” Had he, I wondered, ever spoken to the actual sewermen about these odd journeys beneath the city’s raddled hide. “Oh, no,” he replied, “I think they’d be pretty down on what I do – after all, they wear full oxygen kits and dry suits … ”

Now he told me! But, thankfully, the manhole cover swung wide and we ascended into the street I cycle down almost every week on my way to Blockbuster. The fantastical and chthonic elided effortlessly with the mundane: my favourite experience. Half and hour later, we were eating in Speedy Noodle back in Brixton.

Anyway, there we were, looking frumpy – with the exception of Mrs S and the ever-dapper nephew – in among the slap-headed and pig-tailed balletomanes, when during the first interval a young woman came up and introduced herself as being in the press department at the British Library. “We’ve just acquired JG Ballard’s archive,” she said, “as you probably know, and I thought I’d come and say hello given that some of your letters to him are in it.”

Well, I’m sure you know what Mr Nasty said to that: “Oh, really, I want them back.” Jason Shulman, who was with us, pointed out that I didn’t physically own the letters any more – only the rights to their reproduction – but I still felt uneasy and appropriated. A discussion on the merits of biography followed. Certainly, the biographers of the living are the worst: like anticipatory ghouls waiting for the car crash to happen, but there’s also an argument to be made against literary biography in general. After all, while the lives of individuals who have linked the collective to the individual experience (politicians, soldiers, campaigners etc) offer a prima facie case for the understanding of social and political change, it’s difficult to think of writers – who, for the most part sit typing – as of having the same torque. Not that I don’t read literary biography myself – I do, although guiltily, because for another writer it’s simply a species of pornography: watching someone else beating the creative meat.

Which brings us back to Michael Clark, who came on and did a brief solo jig, and then a curtain call dressed in a banana suit out of Leigh Bowery by … well, a banana.

Lying in bed of a late night, having screened out the drunks wending their way back from the pub and the agonised ecstasy of copulating foxes, and the traffic on the main road, and the bellowing of late jets hunkering down over the metropolis, I was still assailed by that “System armed!”. In a world of intrusions this was one too far. I took it up with my neighbour. “Yeah, yeah,” he agreed, “it is aggravating, but I got the car like that and I can’t figure out how to get rid of it … but I’ll try, really.”

Somehow I don’t think he made that much of an effort; after all, the “System armed!” is of a piece with his weapon dog, and the bars in front of his front door, and the CCTV system, and the fact that he appears not to work regular hours … Still, live and let live, I say: he’s always cheerful, and seems oddly to be a steadying influence on the younger and more feral yoof who wander up and down the street, deranged by their yearning for the unobtainable and their surfeit of boredom. As for “System armed!” over the weeks I’ve come to integrate it into my mental life. “System armed!” the car croaks, and I think to myself, I’m glad – truly I’m glad.

It was typically insensitive of me to call in a vulpine strike on Jah Thatch, who, as everyone knows, was only the passive instrument of historical change rather than its initiator. As for foxes, who but an absurd and sentimental urbanite, who refuses to acknowledge that what’s on the end of his fork is an abused fowl, would characterise these vicious and unprincipled creatures as the vanguard of the revolution? Perhaps now, at long last, after the tragic attack on the baby girls in East London, the long-awaited pogrom against London’s foxes will finally be initiated?

And who better to don the red coat and tootle “Tally-Ho!” than my own local Labour MP Kate Hoey. After all, it was Hoey who chose a superb opportunity to bury bad news, by announcing on the very day that Jean Charles de Menezes was shot dead by armed police at Stockwell tube station in her constituency, that she would be assuming the chairmanship of the Countryside Alliance. Obviously, it’s impractical to hunt urban foxes on horseback, but I can see no reason for not putting the many hundreds of so-called “weapon dogs” who roam the parks hereabout to some sort of useful employment.

And if not the dogs, then why not their owners as well, many of whom are second-generation unemployed – the sons and daughters of people who lost their jobs during the great culling on the 1980s. It would seem an elegant solution to both problems to set these folk to the maintenance of dog packs and the manufacture of hunting tackle. Which brings us neatly full circle: eliminating foxes and unemployment with a single measure. Of course, it leaves Thatcher still alive – but then that’s a given, n’est ce pas?

In Wiltshire for the weekend, the M4 is retrospectively rolled up and stashed away in a carpet warehouse of dead roads. I lie on eiderdown, bluebottles buzzing from meadow through drapes, then round my sleepy head. My sons organise painfully exact tableaux of the D-Day evacuations and I urge them to shoot at the advancing 002. scale Wermacht with air pistols. The man with the neat white moustache who’s obsessed by fishing (Catherine Martell’s husband in Lynch’s Twin Peaks?), stands talking with two of the same – and me – over glasses of elderflower presse. This could perhaps go on forever…

But no, there is late morning, and coffee and toast, and the newspaper with its own rumpled dreamscape. The Prime Minister has been in Cumbria, talking about how a community can get over this sort of thing… Strange, as the Anglican Church withers away, so the executive – who after all appoints the Primate in the first place – takes on the cod-spiritual duties of the established church. No wonder no one can get it right.

There is talk of a new Tory MP, famously dashing, to whom posh totty is attracted like flies to… yet he does nothing. Sometimes… Clovis drawls… I think the asexual hide behind the widespread assumption that they must be gay.

The symptoms are precise: a patch of prismatic distortion grows in the left-hand corner of my visual field, then expands in semicircular bands until it covers the whole field of both eyes (I also have binocular vision due to a strabismus, and so am insistently aware of the duality of my visual field, perhaps this explains my liking for fictions that take place in parallel worlds?), in a pattern that can best be likened to a kaleidoscope. It’s pretty, and would be quite like the effects of a hallucinogen, were it not that instead of euphoria there’s only a dull thrum of a headache. It doesn’t disable me, I don’t have to lie down, it fades fairly rapidly – usually within 20 minutes; yesterday’s all-dayer was an exception – and it appears brought on either by caffeine/physical exertion, or – and most bizarre this – hill walking over 3,000 feet.

Nevertheless, when these migraines first appeared a few years ago, I foolishly embarked on the usual battery of tests courtesy of our great socialised medicine, and ended up seeing an ophthalmology consultant at St Thomas’s in London. They did the test where they squirt a dilator into your eye and then scan the retina (my GP’s assumption was that I had a tear). While the nurse was doing this, the consultant – who appeared to be playing up to some idea of himself – scanned the drawings I’d made in my notebook of what I could see during the attacks. “Didn’t you look at these!” he expostulated. “Haven’t you examined this man’s very helpful drawings!” he berated her: “This man has migraine! This is a classic migraine! We’re wasting his time – and ours!” When he calmed, I asked him who, if not he, I should consult about the kaleidoscopes intermittently rammed in my eyes. “Oh, I don’t know,” he spluttered, “a neurologist, I suppose – if you can be bothered. After all … ” I had told him about the lack of headaches and the 3,000-foot onset point “it’s not like you have a bad case!”

All in all a most gratifying waste of public resources.

***

Newsnight calls asking me to go on this evening to discuss the Cumbrian shootings: ‘We’re looking for someone to speculate on what it is about these remote, rural communities, largely white – ’

“Look,” I interrupt, “I’m going to stop you right there; much as I’d like to come on the programme I know next to nothing about remote, rural, largely white communities – I’m very much your urban, multi-coloured kind of a guy … ”

But am I? After all, plenty of people have been shot dead in the immediate purlieus of my south London home over the past few years, and I know just as little about the socio-cultural nexus of their motivations (if such a thing could be said to exist) as I do about those of this killer. Still, I’m confident someone will be persuaded to shoot their mouth off on Newsnight in my stead – if there’s anyone more trigger-happy than a gun nut, it’s a member of the London commentariat.

Who will listen to this stuff? I’ve never been huge on talking books myself, and back in the day the demographic – older, plusher, Mondeo-folk – seemed to be beyond the horizon of my work … but now? Well, now I am those folk – oh, yes, oh yes indeed. And to confirm this I run into some guy in the street who recalls meeting me first with Barney X (notorious junky) in Oxford in 1980, then in Freddy B’s flat in 1998 (another of the same, and his flat is the setting for Birdy Num Num), and that latterly he is in touch with James Z (notorious junky, the model for Prometheus in the story of the same name). In truth, I can’t remember who this guy is – but given his CV is this surprising? I told him about the book, omitting to mention the strange coincidence: his knowing two of the mise-en-scenes there depicted. I don’t know if he’ll read it – he’s in a half-way house for recovering addicts – but by the time he’s back on his feet, the talking book should be available.

So, five cookies for £2.99 from Millies (three milk chocolate, two white chocolate and lemon – if you’re asking), and then the 16.30 to Bath Spa. In Bath, I ate at Waggaponytail, with all the other little pink-lip-glossed Tamsins and Georgies, oh, a girl like me loves a noodle bar, so she does. One gripe: the green tea was the temperature of dishwater. What is it with me and tea nowadays? It does arouse the most fearful indignation in me, the way that on the trains they now hand you a cup of hot – not boiling water – and then the tea bag. Am I the only one, or is this a disgusting approximation of the national beverage, dictated to us by the Health & Safety ninnies?

I digress.

Topping’s bookshop in Bath is owned and run by the redoubtable Robert Topping, who was exiled from Waterstone’s in Deansgate after protesting at the introduction of central buying. His two shops – in Bath and Ely – are everything good independents should be: home and welcoming, staffed by erudite and engaging booksellers. Last time I read there, I had people stretching away to either end of the shop, so had to perorate in the round. This time they’d thoughtfully enlisted the local church, St Michael’s-Without-Bath.

The curate was most keen that I not feel restrained within the sacred precincts from delivering my homily wholly unexpurgated. However, there was a quid pro quo: he would lead the extempore congregation in a small prayer before I began. I had no objection at all – after all, it was his gaff, and I’m a militant agnostic. Moreover, as he appealed to his Lord to aid and assist my creativity, I felt a great surge of scurrilousness building up in me, and became convinced that my satirical weapons were being mightily honed. Who knows, I may yet become a regular communicant.