"These are going back." I hand over the files, and he painstakingly inscribes their numbers on a battered plywood clipboard using a stub of pencil sellotaped to a length of string. "And I'm going with them."

He stares at me, unblinking. "Document number," he says.

I roll my eyes. "Give me that." Taking the clipboard I make up a shelf reference number and write it down in the next space, then copy it onto my left wrist with a pen. "See? I am a document. Take me."

"Document . . . number . . ." His eyes cross for a moment: "Come." He puts his hands to the handcart and begins to push it along, then glances back at me anxiously. "Come?"

For an RHR he's remarkably communicative. I tag along behind him as he finishes his round, collecting and distributing brown manila envelopes that smell of dust and long-forgotten secrets. We leave the department behind, heading for the service lifts at the back; Rita doesn't even raise her head to nod as I walk past.

The heavy freight lift takes forever to descend into the subbasement, creaking and clanking. The lights flicker with the harsh edge of fluorescent tubes on the verge of burnout, and the ventilation fans provide a background white buzz of noise that sets my teeth on edge. There's nobody and nothing down here except for storerooms and supply lockers: people visit, but only the dead stay.

Handcart man shuffles down a narrow passage lined with fire doors. Pausing before one, he produces an antiquated-looking key and unlocks a padlock-and-chain from around the crash bar. Then he pushes his cart through into a dimly lit space beyond.

"How do you re-lock that?" I ask him.

"Lock . . . at night," he mumbles, throwing a big switch like a circuit breaker that's mounted on the wall just inside the door.

We're in a narrow, long room with a couple of handcarts parked along one wall. The other side of the room is strange. There's a depression in the floor, and a hole in each of the narrow ends: rails run along the depression between the holes. Such is the wildly unusual scale of it all that it takes me several seconds to blink it back into the correct perspective and see that I'm standing on the platform of an underground railway station—a narrow-gauge system with tracks about sixty centimeters apart, and an electrified third rail. I hear a sullen rumbling from one of the tunnel mouths, and feel a warm breath of wind on my face, like the belch of a very small dragon. The original MailRail track only ran east to west, but extensions were planned back in the 1920s; I suppose I shouldn't be surprised to find one here, for what else would commend this extremely boring sixties office block to the Laundry as a temporary headquarters?

I look at handcart man. "Can I ride this?" I ask.