I'm responsible for the order and condition of the tent for this week, so you fellows will have to step around to keep the tent in style to suit me." "Oh, if you're tent orderly," laughed Anstey, "then we don't have to take the word from you." "You don't ?" demanded Prescott.
"No, indeed.

If you're the orderly, then you're merely a striker." A "striker," in the Army, is an enlisted man who is paid by an officer for doing servant's work in spare time.

Hence, a striker is, in general, anyone engaged in menial service.
"Come on, Holmesy," urged Anstey, rising.

"We'll go out for a stroll.

Striker, see to it that you have a flawless tent interior when we return." In his glee Anstey seized Greg by one arm and started to rush him out of the tent.
"Oh, all right; go along," gibed Dick.