Who is Campbell from Collected Short Stories Volume Three and what is their importance? W._Somerset_Maugham English & Literature Campbell | Collected Short Stories Volume Three

Campbell is one of the patients at the Sanatorium who has lived there the longest. His competitor is McLeod, who currently believes it is he who inhabits the best room at the hospital. Campbell claims to be waiting for McLeod to die or move out so that he can inherit McLeod's room. As a way to frustrate McLeod, Campbell plays the same tune on his violin repetitively.