The wand of Isobel McGonagall (née Ross) was of an unknown length, wood and core materials. Like most wizards and witches in Great Britain, she likely purchased it at the age of eleven before beginning her education at Hogwarts School. After her marriage to Muggle Presbyterian minister Robert McGonagall, Isobel decided not to tell him of her magical nature. She thus locked her wand in a box under her bed, and retrieved it only upon her first daughter, Minerva's, birth when the infant witch displayed signs of witchcraft she could not conceal from her husband.