As the coach stopped, he smelled the acrid scent of coal smoke cutting through the general fetor, and heard what sounded like a dragon having difficulty sleeping, a kind of chuffing noise, very repetitive, and then suddenly there was a scream, as if the biggest kettle in the world had got very, very angry.

Lord Vetinari tapped Moist on the shoulder and said, ‘Sir Harry tells me that the thing is quite docile if handled with care. Shall we go and have a look? You first, of course, Mister Lipwig.’

He pointed to the sheds, and as they got nearer the smell of coal smoke got thicker, and the almost liquid chuffing noise got louder. Moist thought, well it was a mechanism, that’s what it was, wasn’t it? Merely a thing like a clock, yes, just a mechanism, and so he straightened up and walked fearlessly, on the outside at least, towards the door where a young man with a greasy hat and an even more greasy overall was beckoning with a greasy grin like a fox looking speculatively at some chickens. It seemed they were expected.

Harry came bustling out and said, ‘Greetings, my lord … Mister Lipwig. Please come and meet my new associate, Mister Dick Simnel.’

Behind them, inside the shed, was the shuddering metallic monster, and it was alive. It really was alive! The thought lodged instantly in Moist’s brain. He smelled its breath and heard its voice. Yes, life; strange life but nonetheless life of a sort. Every part of it was subtly shaking and moving, almost dancing by itself, a thing alive, and waiting.

Behind the beast, in the shed, he saw wagons, presumably ready to be towed, and he thought, yes, it’s an iron horse. All around it were acolytes: men working on lathes, hammering on metal, running backwards and forwards with buckets of grease and cans of oil and occasionally pieces of wood which, right now, looked out of place amongst all the iron. And there was a strong sense of purpose that meant we want something done and we want it done fast.

Dick Simnel smiled broadly from behind a mask of grease and said, ‘’ow do you do, sirs. Well, ’ere she is! Nowt to be afraid of! Her name, technically, is Number One, but I call ’er Iron Girder! She’s my machine. I made her, every little bit: nuts, bolts, flanges and not to forget each and every rivet. Thousands of ’em! And all the glasswork too. Very important, your sight glasses and gauges. Had to design everything meself because no one has ever done it before.’

‘And when you give her rails she’ll move more freight than a battalion of trolls, and get there much faster to boot,’ said Sir Harry, standing behind Moist. And he added, ‘It’s true. I swear that young Simnel tinkers with Iron Girder all the time: tinker, tinker, tinker. An overhaul every day.’ He laughed and said, ‘I wouldn’t be surprised if he eventually got her to fly.’