There would be a whirr. Tiny, sensitive pistons reacted to the pressure. Powered by steam driven up from the vast basement boilers, gentle little cogs rotated the length of the card. Where their spring-loaded teeth found sections cut from the thick board, they slotted neatly inside for a moment, and a minuscule switch was thrown further along the mechanism. When the wheels had completed their brief passage, the combination of on-off switches translated into binary instructions that raced in flows of steam and current along tubes and cables to hidden analytical engines.

The cage jerked free of its moorings and began a swift, swinging passage beneath the skin of Parliament. It would travel the hidden tunnels up or down or sideways or diagonally, changing direction, transferring jerkily to new chains, for five seconds, thirty seconds, two minutes or more, until it arrived, slamming into a bell to announce itself. Another sliding door opened before it, and the crate was pulled out into its destination. Far away, a new cage swung into place outside the clerk’s room.

The Acquisitions clerk worked quickly. He had logged and sent on almost all the assorted oddities before him within fifteen minutes. That was when he saw one of the few remaining parcels shaking oddly. He stopped scribbling and prodded it.

The stamps that adorned it declared it newly arrived from some merchant ship, the name obscured. Neatly printed across the front of the package was its destination: Dr. M. Barbile, Research and Development. The clerk heard a scraping. He hesitated a moment, then gingerly untied the string that bound it and peered inside.

Inside, in a nest of paper shavings that they nudged fitfully, were a mass of fat grubs bigger than his thumb.

The clerk recoiled and his eyes widened behind his glasses. The grubs were astonishingly coloured, beautiful dark reds and greens with the iridescence of peacock feathers. They floundered and wriggled to keep themselves on their stubby, sticky legs. Thick antennae poked from their heads, above a tiny mouthpiece. The hind part of their body was covered in multicoloured hairs that bristled and seemed coated in thin glue.

The fat little creatures undulated blindly.

The clerk saw, too late, a tattered invoice attached to the back of the box, half-destroyed in transit. Any invoiced package he was supposed to record as whatever was listed, and send on without opening.

Shit, he thought nervously. He unfolded the torn halves of the invoice. It was still quite legible.

SM caterpillars x 5. That was all.

The clerk sat back and pondered for a moment, watching the hairy little creatures crawl over each other and the paper they sat in.

Caterpillars? he thought, and grinned fleetingly, anxiously. He kept glancing at the corridor before him.

Rare caterpillars . . . Some foreign breed, he thought.

He remembered the whispers in the pub, the winks and nods. He’d heard a chap at his local offering money for such creatures . . . The rarer the better, he’d said . . .