The Casebook of Charlotte Holmes (1977)

Charlotte Holmes is a young 12-year-old noble girl who loves to investigate cases. One day, she stumbles upon a case of robbery which involves the Queen of England's ring that had gone missing during a garden party. Rewarded with a new title of honorary detective and a pendant an emblem of recognition, she embarks on an adventure. She is assisted by Inspector Jackson, a detective of the Scotland Yard, his dashing assistant Michael, and Charlotte's best friend Franck. They are going to settle numerous problems and bring peace back into the town.