The Quidditch and flying teacher's office was not located in the school itself. Instead it was out underneath the stands of the Quidditch pitch. James Potter sat in his swirling office chair and spun it towards the canvas entry opening, which allowed him quite a view of the pitch. The opening could be transfigured into an actual door when the weather grew unpleasant. James had just been hired to teach at Hogwarts, which was incredible because he was supposed to be dead.
James's door had an invitation on it for people to come and see him that was good anytime he was in his office. That was often, but a guy did have other things to do, like sleep and bother his friend Professor Lupin. And when he wasn't in his office, people werwe invited to leave him a message. He would get back to them as soon as he could. Merlin, that sounded like an answering machine.
The Wild world of Hogwarts years 1 through 7
Harry Potter Role playing guild