Everybody’s hot at St Raymond’s primary school near Liverpool. It’s still morning, but the windows are open and girls are blowing away strands of hair to get some air circulating. If pupils are bothered, they’re not showing it, because Frank’s reading and they want to listen. Frank Cottrell Boyce, that is; this year’s winner of the CILIP Carnegie Medal for his novel Millions.

He’s reading from his new novel Framed about the last boy left in a Welsh village. Like Millions - and the novelist himself - it is tender and funny, revelling in the outlandish and untoward. He explains that as the book’s not being published until September, he’s reading from an uncorrected proof so there could even be changes. The honour of a preview is not lost on his audience and in turn Cottrell Boyce is touched by their attention. He’s been coming into the school in Netherton for almost a year and this successful and seasoned screenwriter (but first-time novelist) feels entirely answerable to his audience there: “As a screenwriter you are invisible, but as a children’s novelist you have to stand by your work.”

St Raymond’s serves a poor local authority housing estate with no other resources apart from a Spar and a moby (grocery van), and Cottrell Boyce is most concerned that his narratives should hit the spot and spark imaginations.

He is discovering the power a writer has to make readers: Millions was a film script before it was a book. It is the bittersweet story of two brothers and their dilemmas when a bagful of stolen cash comes crashing into their lives with only days left to spend it before Britain converts to the Euro. Danny Boyle, director of edgy cult films such as Trainspotting and Shallow Grave, seemed an unlikely children’s film-maker, but he was attracted by the story’s darker depths, with its underlying themes about moral choices and bereavement and the visual potential of young Damian’s obsession with saints. Boyle also saw a novel in it. Cottrell Boyce says:

“As soon as Danny said I should try writing it as a book, it was like someone had turned on a light. I loved writing it.”

Throughout the novel, young Damian has visions and conversations with a litany of saints such as St Peter: “the patron saint of keys and locks and security arrangements in generalIOn top of that fishermen, popes, RomeII am run off my (swear) feet. I’m supposed to mind the gates too you know.”

Young readers have been mesmerised not only by thoughts of how they’d spend all that money in such a short time, but also by the characters of the saints. Millions has been chosen as the next book for Liverpool Reads, a citywide reading programme, from October (the scheme started last year with Louis Sachar’s Holes) and already saints’ trails around Merseyside are on the agenda.

Cottrell Boyce has grown up in the Catholic faith and its great repository of narratives. His family would constantly call on the saints to intercede in their lives, especially St Anthony, patron saint of lost things. For the author, drawing on these stories was like “narrative cash”, and while writing the novel he would often retire to the toilet with a dictionary of saints. Stories of the saints, he says, constitute “a repository of Western folklore for the past 2,000 years”. The saints he’s thinking of are not so much pious as “rough as guts” and “extremely troublesome”. Part of their appeal for modern readers, he believes, is “the buzz of the arcane, like the wizardry stuff in Harry Potter”.

Frank Cottrell Boyce is an Oxford English graduate (he completed a PhD on English Civil War pamphlets when in a “more serious frame of mind”) who went on to write scripts for Brookside and Coronation Street before going into film. He was encouraged to write by a nun who taught him at primary school. At his secondary school, the Christian Brothers’ De La Salle in St Helens near Liverpool, his English teacher made Punch and Judy puppets and commandeered the young Frank to provide the voices and the script. He spent his gap year on the Punch and Judy circuit “improvising with the tight structure of a tale that hasn’t changed for the past 300 years”. The story of the boys with the stolen cash, he says, is straight out of Chaucer’s Pardoner’s Tale.

When Cottrell Boyce made a film with St Raymond’s pupils (which was shown alongside Millions at a Bafta preview at the Liverpool Odeon) they chose to illustrate their tale of a boy lost in the woods: “straight out of ‘Hansel and Gretel’, the woods being where bad stuff happens.” Indeed, for many of the children who had rarely strayed out of Netherton, filming on location in Formby woods was scary in itself. In this way Cottrell Boyce made pupils realise they were well tuned into literary history and capable of literary invention. Rita Coyne, St Raymond’s literacy co-ordinator, says: “Frank treated the pupils as equals and gave them a respect for literary skills.

Even some of our most reluctant boys now want to read and write.”

Millions is like a parable with dark corners and sharp edges. It deals with what Cottrell Boyce, a father of seven, sees as the “horrifying extent” to which money has invaded young people’s lives. Perhaps that is why all the proceeds from the talks he and Danny Boyle give on the book and the film go straight to Wateraid (Damian’s quest to raise money for wells features significantly in the novel). Up to $80,000 (pound;46,000) has been raised from film question-and-answer sessions in the US alone.

Joining the Carnegie winners’ list, Cottrell Boyce says, was like “winning the World Cup without realising you were playing. All my happy childhood memories are in that list.”

Millions by Frank Cottrell Boyce is published by Macmillan Children’s Books