One response to our stunned impotence in the face of financial meltdown, political chicanery and the creeping surveillance society, is to indulge in fugues of entropy tourism. Badlands dérives. Websites clanking with scrap metal, the refuse of military hardware, sump-oil lakes, pastiche Tarkovsky. The recent invasion of the Lower Lea Valley (the Olympics site) by fork-tongued instruments of global capitalism, hellbent on improving the image of destruction, has been duplicated by raiding parties bearing cameras and notebooks, the tattered footsoldiers of anarchy: retro-geographers, punk Vorticists. Sentimentalists of every stripe are undertaking knotweed rambles as pilgrimages to rescue the last remnants of locality by reciting threatened names made sacred by generations of unacknowledged predecessors: Hackney Wick, Temple Mills, Isle of Dogs. Every trudge around the perimeter fence of the Australian super-mall and its satellite stadium is a recapitulation of William Blake's itinerary, as laid out in his mythopoeic masterpiece, Jerusalem: "thro' Hackney & Holloway towards London / Till he came to old Stratford, & thence to Stepney & the Isle / Of Leutha's Dogs".

Old Stratford, transport hub, retail cathedral, birthplace of the Jesuit poet, Gerard Manley Hopkins, drew me back with its intimations of a new England, a city state outside time and beyond culture. Compulsory diversions have been arranged, systems of barricades and cones, to funnel random pedestrians through chasms of glass and steel towards the shimmering illusion of the Westfield oasis. It took something special to make me reach for my camera, all the evidence had already been logged and relogged. Just as my futile presence, in its turn, was captured on hours of security tape, scans from overhead drones.

Walking away from the revamped container stack looking over the Olympic stadium, I found something worth recording. The poster with the smirking, corkscrew-haired young woman chosen to promote another meaningless development opportunity had been customised with black pennies over the eyes, stickers announcing: "SAVAGE MESSIAH". Was this a band paying their respects to Henri Gaudier-Brzeska? (Savage Messiah is the title of a biography of the sculptor, by HS Ede, published in 1931.) Or was it an art school tribute to the subversive dynamism of Blast and Wyndham Lewis? In a shallow, fast-twitch period we thrive on commodified speed-dating, quoting the quote, Xeroxing energy sources to make them into marketable brands. If Ede's book was not the inspiration, perhaps the neo-Vorticists of Stratford had chanced on Ken Russell's 1972 film with the same title, scripted by the poet Christopher Logue, and featuring Dorothy Tutin and Scott Antony as the fated pair, Gaudier and his Polish lover, the troubled Sophie Brzeska?

The mystery of the defaced poster was solved when I discovered Laura Oldfield Ford's samizdat pamphlets, recording moody expeditions, pub crawls, mooches through the kingdom of the dead that is liminal London. Even the author's name seemed like a serendipitous marriage of Blake's Old Ford and the poet Charles Olson's notion of open-field poetics (the contrary of the current fetish for enclosures). The original Savage Messiah "zines" are serial diaries of ranting and posing among ruins. Ford delivers the prose equivalent of a photo-romance in quest of a savage messiah with attitude, cheekbones and wolverine eyes. A feral, leather-jacketed manifestation of place.

Collided into a great block, the catalogue of urban rambles takes on a new identity as a fractured novel of the city. Slim pamphlets, now curated and glossily repackaged, have an awkward relationship with their guerrilla source. With a formal introduction and a cover price a penny short of £20, it is difficult to sustain the swagger of the throwaway form, strategically manipulated to look like dirty sheets on which you can smell the ink, glue, semen and toxic mud. The structure depends on a steady drip-feed of quotes from JG Ballard, Italo Calvino, Guy Debord, Walter Benjamin. White men all, festering in elective suburbs of hell, where they labour to finesse a paradise park of language.

Moving beyond this relentless Xeroxing of the entire genealogy of protest from Blast to Sniffin' Glue, by way of Situationism and psychogeography, Oldfield Ford displays authentic gifts as a recorder and mapper of terrain. She is a necessary kind of writer, smart enough to bring document and poetry together in a scissors-and-paste, post-authorial form. Like so many before her, psychotic or inspired, she trudges far enough to dissolve ego and to identify with the non-spaces into which she is voyaging. "This unknown territory has become my biography." Her story is eroticised by the prospect of riot, anecdotes teased from smouldering industrial relics. The "euphoric levitation" of brutalist tower blocks. Post-coital reveries from "an ugly night on ketamine in a New Cross squat".

Alongside the standard tropes of entropy tourism, talk of "mystical portals", Heathrow as a "mesh of paranoia", Oldfield Ford experiences sudden illuminating shifts of consciousness. "The air is perfumed, the sky pink. My hair is loose, unkempt, I am in a red dress descending into the chlorine scent of a disused pool." Ballardian riffs anticipate plague, soul sickness, breakdown of the social contract. "There wasn't a fixed point where the malaise started." In the end, it's about walking as a way of writing, recomposing London by experiencing its secret signs and obstacles.

When writers identify with the city that feeds and sustains them, they become plural. They abdicate originality. Sophie Brzeska, after Gaudier had been killed in the first world war, embarked on a London walk as random and driven as anything undertaken by Oldfield Ford. As Ede reports: "She walked all through the night  talking and swearing more loudly than ever  a strange, gaunt woman with short hair, no hat, and shoes cut into the form of sandals. She felt the world was against her."

 Iain Sinclair's Ghost Milk: Calling Time on the Grand Project is published by Hamish Hamilton.