I’m more confused by this comment: “it would hardly be the first time that a general and a president have not got on like a house on fire.” I don’t know if that’s a British saying or the invention of this particular writer, but it sounds weird.
Getting on like a house on fire means getting along very well. The reasons as to how such phrase which on the face of it sounds so condradictory to its actual meaning seems to be lost in the mists of time.
Perhaps it is a reference to how close the flames and the house are to each other and in such a spectacular fashion or something...