On a summer's day in 1974, Norwegian actor Knut Risan steps up to the mic for a voiceover job. It's for a Cinderella movie that's just been acquired by the Norwegian broadcaster NRK, from the country known at the time as Czechoslovakia.

NRK want him to dub the film into Norwegian. Knut's just having fun. He's doing all the voices, even the young Cinderella. But he's about to become Norway's "Voice of Christmas" when NRK decides to put the film out as part of its festive line up.

Tři oříšky pro Popelku or, as it's often translated, Three (Hazel)nuts for Cinderella, remains an essential part of many Europeans' seasonal viewing to this day. Not least in Norway, where it is shown at 11am on Christmas Eve every year.

Knut's son, Olav, used to feel a little embarrassed around this time of year - everyone knew he was the son of the most famous voice on TV. He'd get strange looks in supermarkets. But today, and in this episode of Sideways, he reflects on the special place his father's voice occupies in Norway's Christmas and in his own family.

Through the story of a film that straddles the line between fairy tale fun and the realities of the Iron Curtain, Matthew Syed explores the origins, meaning and persistence of this cross-cultural tradition and celebrates the role of Christmas films in many families' celebrations, including his own.

Featuring musician Olav Risan and author Kathrin Miebach of the Drei Haselnüsse für Aschenbrödel website. With fairy tale expert Professor Claudia Schwabe of Utah State University and Michal Bregant, Director of Národního Filmového Archivu.

Including clips from Tři oříšky pro Popelku (Czech language version) and Tre nøtter til Askepott (Norwegian language version, featuring the voice of Knut Risan). Tři oříšky pro Popelku directed by Václav Vorlícek and starring Libuse Safránková and Pavel Trávnícek. Written by Božena Němcová (story) and František Pavlíček (screenplay), produced by Jiří Krejčík and with a score by Karel Svoboda. Distributed by Ústřední půjčovna filmů.

Presenter: Matthew Syed Producer: Amalie Sortland Series editor: Katherine Godfrey Sound design and mix: Naomi Clarke Theme tune by Ioana Selaru A Novel production for BBC Radio 4