Alan Moore: ‘…if we have any optimism in [Watchmen] it’ll be valid optimism because it won’t simply be based on ignoring the nasty facts of life. To me, just in that last panel, in Godfrey’s last line “I leave it entirely in your hands” – that’s talking to the reader as well… I leave it entirely in your hands, how do we sort out this Gordian Knot? If the question is who makes the world? then if there’s an answer it is that everybody does. Yeah, there’s people that seem to be in more immediate power than others but really the world is an elaborate series of accidents, coincidences and unbelievable synchronicities that people appear to be in control of but… well, think about the events in your own life, the things that have made really dramatic changes in you can be traced back to deciding to pick up a ballpoint pen or not pick it up.’

‘Fat is the bane of flushers’ lives. Millions of litres, from half-eaten breakfast dishes, chip-laden frying pans or fast-food joints, are tipped into sinks each day. Eventually they find their way into the sewers. They represent the effluence of affluence. They are the graffiti that the contemporary leisurepolis scrawls on subterranean environments. Thirty years ago the Thames, unloved and abandoned, created few problems for flushers; now, the river’s banks are congested with clubs, boozy eateries and art-complex gallery cafés, all of them disgorging fat.

I wade through some of it at Victoria Embankment. It is at once crunchy and spongy, like putrid bran. Brown and white and grey: a pigeon-shit potage sprinkled with an extra top layer of mop heads and tampons. Flushers tell stories of accidentally getting a gobful of the sewer flies that feed on the fat or of metal grating giving way so that they fall into eight-feet-deep fat-quicksands; the mouthfuls of the stuff they swallow leave their guts raw and hollering for months on end.

But it’s the bouquet that makes their flesh crawl: “You smell it initially. You breathe it all day long. You pass wind and what comes out is the smell of the fat. You can go home and shower as much you like – even with washing-up liquid – but at the end of the day you’re still farting the smell of rancid fat. My wife’ll say: ‘Oh, I see you’ve been sorting fat problems out?'”‘