The Frenchman’s smile was so charming that the Broekharts could not take offence.

‘Well, Captain,’ said Vigny, sweeping back his arm dramatically to introduce his balloon. ‘I give you Le Soleil, the Sun. What do you think of her?’

The dirigible was undeniably magnificent. An elongated golden envelope swaying gently over its leather-bound basket. But Declan Broekhart was not interested in decoration, he was interested in specification.

‘A bit more pointed than others l’ve seen,’ he noted.

‘Aérodynamiqué,’ corrected Vigny. ‘She glides across the sky like her namesake.’

Catherine unhooked herself from her husband’s arm.

‘A cotton-silk blend,’ she said, craning her head back to squint at the balloon. ‘And twin screws on the basket. A neat piece of work. How fast does she travel?’

Vigny was surprised to hear such technical observations from a female, but he disguised his shock with a few rapid blinks, then smoothly delivered his answer.

‘Ten miles an hour. With the help of God and a fair wind.’

Catherine peeled back a corner of leather, revealing the woven basket underneath.

‘Wicker and willow,’ she said. ‘Makes a nice cushion.’

Vigny was enchanted. ‘Yes. Absolument. This basket will last for five hundred hours in the sky. French baskets are the best in the world.’

‘Très bien,’ said Catherine.

She hoisted her petticoats and climbed the wooden steps to the basket, displaying remarkable agility for a woman eight months’ pregnant. Both men stepped forward to object, but Catherine did not give them time to speak.

‘I dare say I know more about the science of aeronautics than both of you. And I really don’t think I have crossed the Celtic Sea to stand in a glorified field while my husband experiences one of the wonders of the world.’