The moon smiled down like a Cheshire cat, as excited children pulled their relieved and confused grown-ups towards the boating lake in the middle of the park. Soon the lakeside was lined with people.

Without being asked, the Ice Children, all 209 of them, stepped forward and joined hands. They remembered well the tears that had brought them home to their families and the promise they’d made to Ishild, the melting Snow Queen.

Closing their eyes, each child painted a picture of Winterton in their mind, remembering their feelings of joy and wonder at being there. As they did this, the boating lake at their feet transformed from a midnight liquid to a moonlit solid.

A woman screamed as two polar bears appeared from nowhere, skating out onto the ice on all fours before reaching out, clasping paws and pirouetting as a pair. The boating house had become an igloo, and a pair of puffins squawked, waving their wings excitedly at the ice skates on the shelf behind them.

‘What is this?’ Bianca’s mum asked in amazement.

‘Winter.’ Bianca sighed happily, looking at all the reunited families around the lakeside.

There were gasps as the twinkling Flurry Flake appeared beyond the bandstand, and awed murmurs as the ground grew a blanket of thick snow. A hot-chocolate fountain materialized in the middle of the rose garden, and marshmallows bloomed on the bushes.

The Ice Children grabbed the hands of their grown-ups, gabbling excitedly that they’d really only been away for a day, and that they’d been playing in the wonderful Winterton.

Bianca smiled as she saw Casper take his dad’s hand, leading him towards the rock garden, which had become a stony path that she knew would lead down to the sea, and the cove where Monodon would be waiting.

‘Bianca!’ came a voice inside her head, and she turned to see her Pordis standing there. She threw her arms round the reindeer, unable to prevent herself from sobbing. ‘You mustn’t cry, Bianca. I am always with you. You are my herd.’

Hearing Finn laughing, Bianca looked up to see Sposh bouncing around her dad’s feet. All around her, she heard cries of wonder and shrieks of delight.

A battalion of grown-ups was frantically making snowballs, suddenly as wild and carefree as their children. Bianca saw the doctor in his woollen coat shouting orders as he hurled the first snowball, and a new snow battle began. The polar bears on the frozen boating lake were giving skating classes to little ones, a unit of police officers was building a snowman and the helter-skelter had a queue of smiling people all drinking from their tin mugs, which brimmed with marshmallow-sprinkled hot chocolate.

Bianca heard the delicate chimes of sleigh bells.

‘Look!’ Sophie Lilley cried, and everyone turned their eyes skywards. Fat, puffy flakes of snow drifted down to kiss their cheeks.

‘A unicorn!’ Mrs Dorcas, the librarian, shrieked with excitement, clenching her fists and turning purple, as if she were about to explode with joy.

A choir of amazed sighs accompanied the Snow Queen’s sparkling sleigh as it descended through the clouds and landed beside the frozen lake. Two snow golems rose from a snowdrift, one attending to the unicorn, the other standing ready with its hand outstretched, ready to assist Ishild.

All the Ice Children knelt, and the grown-ups, after glancing around, did the same.

Ishild stepped out of her sleigh, Snow personified, powerful and unmelting, hovering above the ground, surveying the gathering of humans.

‘Tonight is the longest night of the year,’ Ishild said in a voice with many notes, like the song of a wind harp. ‘Let us spend it celebrating winter like we have never celebrated before, so that people will tell stories of this night for centuries to come and the memory will live long in your hearts!’

There was a high trill from the bandstand, and Bianca saw the Arctic orchestra was ready to play. The Arctic fox lifted her silver flute and the snowy owl began pecking away at the string of icicles hanging from the bandstand roof. The musk ox hummed a bass note and the walrus slapped at his blubbery belly.

Jack slid across the ice, reaching out a hand to Ishild. Whirling each other in silver-dusted arms, Snow and Frost flew across the lake, dancing a tango. They turned their heads, kicked up their legs and spun away from each other in a breathtaking routine. Pitter and Patter’s feet rose and fell, landing slowly at first, building to a furious rhythm to accompany the dancers, their heads bobbing as they jigged along the shore. Standing beside the unicorn, Quilo jiggled his shoulders, and popped his bottom from side to side, in a time signature all of his own making.

‘Come on, Yanka,’ Finn cried, grabbing Bianca’s hand and dragging her onto the ice to join in the merriment. She laughed as he bent his knees and threw his hands in the air as if he were trying to shake off a nest of biting ants. A heartbeat later, their dad and mum were there too, spinning around them, gasping and laughing as their children wriggled their shoulders and pulled faces to the undulating tunes of the Arctic animal orchestra. The Ice Children and their families danced the night away with the Frost, the Hail, the Sleet, the North Wind and the Snow, and it went down in the history books as the wildest winter party the city had ever seen.