“Safe assumption.”

The carriage in question – a gilt horse-drawn affair, like something from a nursery rhyme, complete with trailing blue ribbons and enamel panels depicting beautiful romantic tableaux of goose girls and Greek heroes – pulled up next to them. Percy, an incongruous occupant for even the most ordinary of carriages, unfolded from within, rumpled and harried. He still wore his favourite smoking jacket, although he had substituted cream linen trousers for the tweed with the result that he looked rather like a cricket player cross-bred with a librarian. He’d forgotten a hat and his red hair was sticking up wildly in all directions in a fair imitation of a werewolf after full moon night.

His little valet followed. Virgil’s eyes were wide and mouth slightly open as he caught sight of the dirigible and the chaos of luggage surrounding it.

The Spotted Custard now boasted a completely finished exterior. Her balloon had indeed been painted bright red with black spots and coated in the necessary lacquers and oils to make her weather-resistant. She shone in the late afternoon light like some large, fat, round seedpod. The trim of the gondola section was picked out in shiny black, a stark contrast to the pale blond wood. Railings and other details shone darkly beautiful in the late afternoon sun. Dama had insisted that black was the perfect choice, being a colour that matched anything. “Now, when you lean picturesquely against the railings, my Puggle, your dress will never clash.”

“Very well reasoned, Dama,” had been Rue’s straight-faced response.

Percy looked about with utter indifference.

“Well, Percy,” said his sister, drawing his attention to her presence. “What do you think?”

“Why name the craft after a comestible and then decorate it like a Coccinellidae?”

Rue knew better than to attempt reasoning with Professor Percival Tunstell. “Because I like it that way.”

Percy wrinkled his nose at her and then, distracted, leapt forward. “Do be careful – those documents are hundreds of years old!”

Rue summoned Percy’s valet with a subtle gesture. “Virgil, be a dear and steer him up that gangplank and down below into the library, would you, please? Spoo here will show you the way.”

Spoo obliging appeared at Rue’s elbow and nodded at the young valet. “Oi up, me duck?” she said, or something equally unintelligible.

Virgil looked askance at the soot-covered girl, near his own age but remarkably scruffy and laddish by comparison. “Good afternoon,” he said, remembering his manners. Then he looked up at Rue, panicked. “Himself won’t like it if this one goes anywhere near those there scrolls.”

Rue grinned. “Ah, good. Spoo, follow those trunks, pretend to be helpful and try to touch them but don’t actually do so.”

“If you say so, captain.” Spoo, irrepressibly good-natured, trotted off to do exactly as she had been instructed.

Percy instantly panicked and ran after the girl as she rendered – what Percy was certain was – smudgy doom upon his trunks and satchels of books. Everything else was forgotten as he followed the sootie’s stubby form in gangly worry. Virgil brought up the rear carrying a wicker picnic basket that was yowling in protest, and a good quality hatbox. At least Percy would have one top hat on board. And his cat.

“Good. That’s him safely ensconced,” said Rue.

“You’re not worried he’ll escape?” Prim watched her brother with affectionate exasperation.

“I’ve given instructions for the footmen and porters to wall him in with his own books. By the time he reads his way out, we should be ready for float off.”

“You’ll leave a feeding hole?”

“I’m not a monster.” Rue looked up in time to see yet another conveyance barrelling towards their not-so-secret location. “Speaking of monsters.”

This contraption was no horse-drawn carriage but a steam-powered locomotive of a most unusual design. It was insect-like in appearance, constructed rather like a pill bug, although it was not intentionally decorated as such – like The Spotted Custard – but only appearing bug-like out of necessity. It was more utilitarian than beautiful, its exterior comprised of darkened metal panels shelling into one another like scales. It belched steam from below this carapace, and smoke from two stiff antennae.

The steam roly-poly subsided to a stop and a hatch at its top popped open. Quesnel Lefoux’s boyish head poked out.

“Good afternoon, ladies.” He tipped his hat. He, of course, was impeccably well turned out.

“Mr Lefoux, how do you do?” Prim gave the inventor a warm smile.

Rue nodded, her own smile slightly forced.

“Like that, is it?” Primrose looked at Rue sideways and then suddenly caught sight of something aboard ship that needed her attention. “Oh dear, my skirt tapes appear to be in some danger. The sooties are turning them into slingshots. If you would excuse me.” With which she opened one of her parasols, a frothy white affair with small green embroidered leaves, and bustled up the gangplank. She was wearing a sage travelling dress with cream lace sleeves and collar decorated with more embroidered leaves. Prim had such an enviably effortless style. She used the second, closed parasol, with equal effortlessness to prod her way through the masses.

Quesnel came over. “And where has the charming Miss Tunstell gone? Was it something I said?”

“Perhaps the cut of your jib offends,” suggested Rue.

“I assure you my jib is very well cut indeed.” Before Rue could sputter he changed the conversation. “I can’t say I approve of what you’ve done with the place. Why the spots?”