Agatha Chubb was a witch and an expert in ancient wizarding artefacts.
While researching Quidditch practises of the 16th century, she recovered no fewer than twelve lead Bludgers from marshes and peat bogs in Great Britain and Ireland. She used this discovery to demonstrate how modern wizards developed Bludgers from lead and then iron, as lead was determined too soft a metal for the purpose of the balls.
She wrote, "They are undoubtedly Bludgers rather than cannon balls. The faint indentations of magically reinforced Beaters' bats are visible and one can see the distinctive hallmarks of manufacture by a wizard (as opposed to a Muggle) - the smoothness of line, the perfect symmetry. A final clue was the fact that each and every one of them whizzed around my study and attempted to knock me to the floor when released from its case."
"Agatha" is a Latinized form of the Greek name Αγαθη (Agathe), derived from Greek αγαθος (agathos) meaning "good". Saint Agatha was a 3rd-century martyr from Sicily who was tortured and killed after spurning the advances of a Roman official. The saint was widely revered in the Middle Ages, and her name has been used throughout Christian Europe (in various spellings). The mystery writer Agatha Christie (1890–1976) was a famous modern bearer of this name.