Moist had travelled fast before. Indeed, a golem horse, that rare creation, could have easily outpaced them. But this, well, this was machinery, handmade by men: wheels, bolts, brass knobs, dials, gauges, steam and the grunting sizzling fire box, beside which Drumknott was standing now, hypnotized and pulling the chain that blew the whistle as if performing a holy duty, and everything shook and continued to shake like a red-hot madhouse.

Lord Vetinari and Harry came into view as the train raced towards them on its first lap. And they disappeared behind Moist into the cloud of smoke and steam left hanging in the air. Then, as Iron Girder plunged on, it broke through into Moist’s consciousness that this wasn’t magic, neither was it brute strength, it was, in fact, ingenuity. Coal and metal and water and steam and smoke, in one glorious harmony. He stood in the fierce heat of the cabin, shovel in hand, watching and wondering about the future, as the train of carriages bumped round once more, screeching slightly on the second curve. Then, with the sound of tortured metal, it slid to a stop a few feet away from the watchers in front of Iron Girder’s shed.

Now Mr Simnel was all arms and business, shutting things down and turning things off as the wonderful engine died. Moist corrected himself: not died – she was sleeping but still dribbling water and hissing steam and, inexplicably, she was very much alive.

Simnel dropped down from the cab on to a makeshift wooden platform and looked at his enormous stopwatch, glanced at the dial and said, ‘Not bad, but I couldn’t really open ’er up round here. On the test track over at Swine Town I got her going at almost seventeen miles an hour, and I can swear that she could go much faster if I could lay down a longer track! And she moved reet wonderfully, didn’t she, gentlemen? With all that load, tons of it.’ This was said to his fellow engineers.

‘Aye, what is it?’ And this, in fact, was directed to a small wide-eyed urchin, who seemed to have miraculously appeared by the side of the track. Simnel looked on gravely as the urchin took out a very small notebook from his jacket pocket and meticulously wrote down the numeral 1 as if it were a command.

And Moist, for some reason, couldn’t help himself from saying, ‘Well spotted, young man, and you know what? I rather feel that you’re going to need a much bigger book before long.’ And the certainty hit him that, although Lord Vetinari’s face was as impassive as ever, those of Harry King and some of the other on lookers were gleaming in the smoky light of the future to come. Given the numbers already lining the fence, straining to watch the train on its circuits of the compound, the news was out and flying.

Harry King said, ‘Well, gents, is this iron horse not amazing? She seems to be able to move anything, I assure you. Now, there’s a nice lunch awaiting us in my boardroom, gentlemen. Shall we go up there? … There’s some cracking good beef.’