After hearing Harry’s complaints, the lawyer said, ‘It’s a matter of patents, Sir Harry. You know, all that fiddly stuff that you said you paid other people to get their heads around? Well, Mister Simnel and I have filed applications for every one of his innovations. But I am sure there is more than one way of building a machine to run on rails. You cannot patent the idea of a railway as such, and if you take a walk down the Street of Cunning Artificers you will find someone quite bright enough to discover how to make a train that will run on rails without infringing any of the patents I have been able to obtain for you.

‘The idea of steam locomotion as such has been there for all to see and we all know that a boiling kettle will try to lift its own lid. Being clever, some young man watching the fire will work out that if he builds a bigger kettle he will be able to lift a bigger kettle lid. Although, as we saw at Effing Forest, he soon learns that it’s not as simple as that. They’re not all as bright and clever as Dick Simnel.’

Harry snorted. ‘Stupid hayseeds. Not a patch on our Dick and his lads. All they’ve done is leave their old mum bound for the poorhouse.’ And Sir Harry harrumphed. A full-blown harrumph.

Unaware that his client was temporarily distracted by the thought of a destitute lady living in the Effing Forest, bereft of her boys, her pride and joy, Thunderbolt continued. ‘Take Mister Simnel’s pressure gauge. Once the principle is proved and understood, the Cunning Artificers, extremely cunning as they are, might well find some way of achieving the same results without breaching patent. It’s what they do. Cunning by name and nature.’

Thunderbolt had got Harry’s attention now. ‘And before you explode, Sir Harry, it is all within the law.’

‘What? After all I’ve done and the money I’ve put in!’ Harry’s face was as red as a beacon. He looked as though he needed one of Dick’s pressure gauges himself.

Moist decided to intervene. ‘Harry, the whole point of trains is that they’re universal. Put them on the tracks and away they go.’

In his mellifluous tones, the lawyer continued. ‘If I were you, Sir Harry, I would simply leave it to me to keep an eye on such things as patents and licences and regulation whilst you and Mister Simnel fill the world with steam. And remember, Sir Harry, the important thing is that you were the first. Nobody can take that away. You, Sir Harry, are on what I believe is called the hog’s back, the top of the heap, the founder of the railway. The Ankh-Morpork and Sto Plains Hygienic Railway Company is as solid as the bank.’