The CBeebies Bedtime Story is broadcast just before 19:00, when the channel aimed at very young children stops broadcasting for the day.
It features celebrities and other well-known personalities reading a short picture book before wishing the audience a good night.
A-list actors such as Tom Hardy, pop stars including Harry Styles and Billie Eilish, as well as sporting heroes Lewis Hamilton and Harry Kane are just some of the names who've sat in the famous CBeebies armchair.
Calum's "audition" clip uploaded to Instagram featured him, in his pyjamas, reading the story of a giraffe born without markings who learns that their differences make them special.