‘And when it’s had enough of a chuffing, there’s enough magnetism to hold the train on the iron road, see?’

The last phrase was delivered in a rush in the hope that no more questions would be forthcoming. But it doesn’t work like that with children. The elder boy had had enough and decided to show off the knowledge gleaned from friends who had been there earlier in the day. ‘Isn’t it to do with reciprocating motions?’ he said, with a glint in his eye.

‘Ah, well, yes,’ blustered Colon helplessly. ‘You’ve got to have your recip-roca-tory motions to get the right kind of chuff. And when everything is chuffing and reciprocatoring, away we go.’

The smaller child was still puzzled, as well he might be. ‘I still don’t understand, mister.’

‘Well, perhaps you’re too young to know,’ said Colon, taking refuge in the excuse used by exasperated adults through the millennia. ‘Very technical stuff, your chuffing. Probably shouldn’t even be trying to explain it to children.’

‘I don’t think I understand either,’ said the mother.

‘You know clockwork?’ said Nobby, coming to the rescue again. ‘It pretty much goes like clockwork, only bigger and faster.’

‘How’s it wound up?’ asked the boy.

‘Ah yes,’ said Colon, ‘that chuffing noise, of course, is the winding up. And when it’s wound up, then off it chuffing goes.’

The smaller boy held up a clockwork engine and said, ‘He’s right, Mum, you wind them up and away they go.’

Bemused, the lady said, ‘Right … well, thank you, gentlemen, for a comprehensive little talk. I’m sure the boys were fascinated.’ And she handed Colon several coins.

Colon and Nobby watched the happy family as they climbed on to the cart behind Iron Girder. And Nobby said, ‘It’s a nice feeling, isn’t it, sarge? Being helpful to people.’

Moist’s cab halted at the palace, and he helped an exhausted Drumknott up the stairs. Amazingly he was beginning to feel sorry for the little chap, who was looking like a lotus eater who had run out of lotuses.^[23]

Moist very carefully knocked on the door of the Patrician’s office, which was opened by one of the dark clerks. The clerk stared at Drumknott and looked askance at Moist, as Lord Vetinari himself stood up in surprise, leaving Moist impaled between two askances. So he saluted smartly and said, ‘I beg to report, sir, that Mister Drumknott very gallantly and fearlessly and at some personal cost has helped me form an opinion as to the practical aspects of the new-fangled train, risking his life repeatedly in so doing, and for my part I have seen to it that your government has a suitable measure of control over the railways. Sir Harry King is funding further research and trials, but personally, my lord, I believe the new railway will be a winner. I’m convinced that this prototype can pull more stock than dozens of horses. Mister Simnel seems to be very thorough in his work, extremely meticulous and, above all, the people appear to have taken the train to their hearts.’