This is not a typo but an unexpected word. On p 232 Mildmay says "So Robin gave Felix a card with the address of the rooms he had on campus"

I find it odd that Mildmay should use the word "campus". He comes from a place with no university and, some pages later, can't even remember the word "university", so I wouldn't think he would associate the word "campus", if he knew it, with a university.