Johnson grew up with the Bobbsey Twins, Nancy Drew, and Trixie Belden, and later became lifelong friends with Miss Marple and Hercules Poirot, Lord Peter Wimsey, Mrs. Bradley, Inspector Alleyn, Inspector Lynley, Chief Inspector Richard Jury, and Superintendent Dalgliesh.

She is currently working of a series of mysteries featuring Lady Serendipity "Sid" Sanbourne, widow of the 11th Earl of Dover, and Detective Chief Inspector Henry Vane. Set in the fictional village of Moreton’s Echoes of the Sea, Cornwall, England in the 2020's, the Sid Sanbourne mysteries are a loving homage to her old friends and their remarkable creators.