Today: three pieces about alter egos, when your name - the words by which the world knows you - is replaced by another for particular purposes.

• How did John Doe come to be the name for a man, alive or dead, identity unknown or concealed in a legal matter? Strap in for a whirlwind ride into some frankly batshit centuries-old English law.

• At their first bout of the 2019 season, the London Roller Girls talk about how they chose their roller derby names - or why they chose to get rid of one.

• The 1930s and 40s were a golden age for detective fiction, which was also very popular and lucrative. Yet writing it was disreputable enough for authors to hide behind pseudonyms.