Someone from an upper class suburb. Rolling Hills is on the Palos Verdes peninsula in LA. Rowe was from one of the New Trier suburbs of Chicago and Moore/Morrow were from Gold Coast of CT.
It's one thing to be wealthy (which Sanderson and some others no doubt were, hockey isn’t cheap), but growing up in a very affluent community just breeds a kid differently. You're expected to go to the kind of school your parents would be proud to mention at the social club or black tie events.