The Final Whistle

Almost at the end of The Final Whistle, which is a tremendous book. Funny, informative, profoundly moving, deeply intriguing. For example, there's Wilfred Jesson (Robert Wilfred Fairey Jesson). A fellow officer wrote after his death, "His company particularly mourned him as he had been father, mother and sister to them..."

Now the father/mother bit I get entirely, as an officer's duty was to ensure (as much as he could) the welfare of his men. But "sister"? I need to know more about him!