Harry has at last found love at Hogwarts. His close friend, Colin Creevey, says that Harry is rarely seen out of the company of one Hermione Granger, a stunningly pretty Muggle-born girl who, like Harry, is one of the top students in the school.
It seems to me that "out of the company of Hermione Granger" is fine. I'm not sure what 'one' is doing there. Any thought?