Despite the thick fog, and with Harriet doing half the remembering, Alice managed to find her way back to the narrow street. On the other side from the workshop, in blurred silhouettes, she made out some boys sitting on a wall, swinging their legs.

One of the group noticed the two girls, and as he shouted the others turned too. ‘Ho there! Ladies!’

‘Come on. There’s no other way.’ Alice pulled Harriet by the hand.

‘We’re looking for Jas and Arthur,’ Alice said, as she approached the group.

‘Jas and Arthur, is it? And d’you think they wanna be looked for?’ The tallest of the boys slithered down from the wall.

Harriet spoke next: ‘We want … to propose something.’

‘It’s proposing now! Mates, they want to propose to Jas and Arthur.’ He brought his face alongside Alice’s. There was a smell of old meat. She shrank back.

She wasn’t even sure whether Jasper and Arthur were among them, but she knew she could not ask any of the other boys instead, especially now that the rest of the group had slithered down and surrounded them. She gripped the package in her hands tightly. She and Harriet had their backs to the wall. The boys varied in height. She sized them up, calculating whether she could grab Harriet’s arm and make a run for it past the shortest one, if she needed to.

‘Are they here?’ she asked again, trying to maintain the volume in her voice. The tall one glanced over her head, towards something further down the street.

‘Oh yes, they are. They’re here. Talk of the devils!’ he said, smiling with a flourish on the final word. He had lost his front teeth. As Alice turned in the direction that he was looking, he called out in a sing-song voice, ‘Jasper, O Jasper. Here are two ladies as wants to propose something.’

Jas and Arthur entered the semi-circle of boys. Neither of them was especially tall, about the same height as the girls, but Jasper had the respect of the others in the group.

‘Hello! You two back?’ Jasper raised his cap.

‘I want to ask you to do something,’ Alice said. ‘It’s an exchange.’

Jasper led the girls away from the group. Alice explained what she wanted, gave the boys the packet she had prepared, and unlocked the workshop door. The two boys entered and closed the door behind them. After a full minute the door re-opened. The boys came out, holding blankets around themselves, and gave Alice a bundle with their shoes sitting on top.

‘Cold in there,’ Jasper said.

‘Especially with our clothes off.’ Arthur giggled.

Alice took the bundle from Jasper and gave each of the two boys a shilling.

‘Thankyou,’ she said. The boys did not seem to know what to say in return. Even though she had the key to the door she waited for Jasper and Arthur to lead the rest of the boys away, so that she and Harriet could get changed.

The girls re-emerged from the workshop transformed. They stared at each other in a mixture of shock and delight. ‘Now we’re ready,’ Alice said. ‘But first I need to return the key.’ Alice took Harriet’s arm and they retraced their steps back to Alice’s street.

They stopped at the corner. Alice approached her house, alert, then ducked below the low garden wall at the front in order to reach the passage at the side. From there, by the side gate, she could reach the back of the house, enter by the kitchen door and replace the workshop key. The fog helped to cover her.

As she was placing her hand on the knob of the kitchen door she heard Miss Simpson’s voice. She had not expected her back this early.

‘Mr Jones, Alice has left a note to say she’s gone to the zoo with Harriet and her governess. Did she mention anything to you about Miss Anderson coming?’

Alice could not hear her father’s reply, but through the window she saw Miss Simpson leave the kitchen. Quickly and quietly, Alice eased the door open and replaced the key on its hook.

They knew they had to move quickly but they decided to walk to the railway station. It would save money. It was liberating to be disguised in boys’ clothes, with their hair pinned up inside the broad cloth caps. As they walked they observed how other boys and young men walked and moved, and they tried to do the same. When there was no-one in earshot they practised lowering their voices, to get the right depth and accent. Each time they asked someone for directions to the station, they had a chance to try out their new identities.

At the station they bought their tickets – third class singles to Rochester – and headed for the platform.

It was Harriet who noticed the Aepyornis. They stopped and stared at its huge body, which filled the front page of The London Standard. It was another newspaper that had beaten William to the story. Even with only a black outline the bird was breathtaking. For the very first time Alice realised how big the news of Jacob’s discovery was.

The train appeared to be full. They found an empty compartment and closed the door behind them just as the platform guard blew his whistle. They sat opposite each other, and burst out laughing. They were breaking the rules, and it was exhilarating.