From the longer Wikipedia page 
Josephine Tey was a pseudonym used by Elizabeth Mackintosh (25 July 1896–13 February 1952) a Scottish author best known for her mystery novels. She also wrote as Gordon Daviot, under which name she wrote plays with an historical theme.
In five of the mystery novels she wrote under the name of Tey, the hero is Scotland Yard Inspector Alan Grant. (Grant appears in a sixth, The Franchise Affair, as a minor character.) The most famous of these is The Daughter of Time, in which Grant, laid up in hospital, has friends research reference books and contemporary documents so that he can puzzle out the mystery of whether King Richard III of England murdered his nephews, the Princes in the Tower. Grant comes to the firm conclusion that King Richard was totally innocent of the death of the Princes.
In 1990, The Daughter of Time was selected by the British-based Crime Writers' Association as the greatest mystery novel of all time; The Franchise Affair was eleventh on the same list of 100 books.
The Franchise Affair also has a historical context: although set in the 1940s, it is based on the 18th-century case of Elizabeth Canning. The Daughter of Time was the last of Tey's books published during her lifetime. A further crime novel, The Singing Sands, was found in her papers and published posthumously.