Simnel brightened and said, ‘I don’t intend on starting me own guild, if that’s what you’re thinking, but if some young lad comes to see me and wants to learn the way of the sliding rule then I’ll do him right. I’ll make ’im an apprentice the old-fashioned way and his hands’ll never be clean again. And I’ll give him indentures until they’re coming out of his flaming teeth, all writ down on vellum, if I can find any. That’s how it should go, and he’ll work for me until I reckon he’s done enough to be a journeyman. That’s how you do it. That’s how you make your trade.

‘When I saw you first, Mister Lipwig, I reckoned you were all mouth and no trousers. And I’ve watched you running around hither and yon and being the grease for the engine of the railway. You ain’t so bad, Mister Lipwig, ain’t so bad at all, but you’d look better with a flatter cap.’

Iron Girder let out a sudden hiss of steam, and the two men, laughing, turned to look at her. There was something new about the engine. Hang on, Moist thought, her shape has changed, hasn’t it? She looks … bigger. I know she’s the prototype and Simnel is forever tweaking things, but somehow I don’t think I ever see the same engine twice. She’s always bigger, better, sleeker.

As Moist was pondering the question he became aware of Simnel beside him shifting from foot to foot. At last Dick said hesitantly, ‘Mister Lipwig, you know that girl with the long blonde hair and pretty smile who sometimes comes into the compound? Who is she? She acts as if she owns the place.’

‘That,’ said Moist, ‘is Emily, Harry King’s favourite niece, not married yet.’

‘Oh,’ said Simnel. ‘The other day she brought me out tea – and a bun!’

Moist looked at the worried face of Dick Simnel, who was suddenly in a place where the sliding rule couldn’t go. No, this was a different kind of rule, and so he said, ‘Would you care to take a walk with her, Dick?’

Simnel blushed, if a blush could actually be seen under all the grease. ‘Aye, I really would, but she’s all smart and dandy as a daisy and I’m—’

‘Stop right there!’ said Moist. ‘If you’re going to say that you’re just a bloke in greasy dungarees I’d like to draw your attention to the fact that you own a very big slice of all the revenue the railway is ever going to make. So don’t go around saying “Oh dear me I’m too poor to even think about making advances to a nice young lady,” because you’re the best catch that any young lady in Ankh-Morpork could ever find, and I imagine that even Harry, in the circumstances, wouldn’t throw you down the stairs as he did with the swains who were the suitors of his daughters. If you’d like to go walking out with Emily I’d say go to it and I’m sure her uncle and parents will be overjoyed.’