In the plush comfort of Harry King’s boardroom, all mahogany and brass and extremely attentive waiters, Lord Vetinari said, ‘Tell me, Mister Simnel, could your engine go all the way to, let us say, somewhere like Uberwald?’

Simnel appeared to cogitate for a moment and then said, ‘I don’t see why not, your worship. It might get tricky round about Skund and, of course, it gets a bit steeper further on, but I’d say the dwarfs know how to knock damn great ’oles in t’scenery when they want to. So yes, sir, I’m certain it’s possible, in time, with a big enough engine.’ He beamed and said, ‘If we have t’coal and t’water, and t’tracks, a locomotive engine could take you anywhere you wanted.’

‘And is it open to anyone to build an engine?’ said Vetinari suspiciously.

Simnel brightened up and said, ‘Oh, aye sir, they can try, but they ain’t had none of my secrets, and we Simnels’ve been working on steam for years. We’ve learned by our mistakes. They can learn by theirs.’

The Patrician smiled faintly. ‘A man after my own heart, though laminating oneself to the roof of one’s workshop is such a finite lesson!’

‘Yes, I know, but if I might be so bold, sir,’ Simnel continued, ‘I’d like to bid for t’Post Office work, right here and now. Strike while t’iron’s hot, that’s always been the Simnel motto. I know the clacks can send a message as fast as lightning, but it can’t do parcels and it can’t do people.’

Lord Vetinari’s face gave nothing away, and then he said, ‘Oh really? I strike when I like, but never mind, Mister Simnel. I will not stand in the way of your exploring possibilities with Mister Lipwig, but I suggest we must also consider the position of the coachmen and farriers in this time of change.’

Yes, Moist thought, there would be changes. You’d still find horses in town and Iron Girder couldn’t plough, although for a certainty Mr Simnel could make her do so. ‘Some people will lose out and others will benefit, but hasn’t that been happening since the dawn of time?’ he said out loud. ‘After all, at the beginning there was the man who could make stone tools, and then along came the man who made bronze and so the first man had to either learn to make bronze too, or get into a different line of work completely. And the man who could work bronze would be put out of work by the man who could work iron. And just as that man was congratulating himself for being a smarty-pants, along came the man who made steel. It’s like a sort of dance, where no one dares stop because if you did stop you’d be left behind. But isn’t that just the world in a nutshell?’

Vetinari turned to Simnel. ‘Young man, I must ask you, what do you intend to do next?’

‘There’s that many people wanting to see Iron Girder up close like, I thought mebbe I’d hitch up t’wagons and put in some little seats, and offer them all the chance of a ride behind her. If Sir Harry’s agreeable, that is.’