In the First World War, nurses like Mabel (and my grandma) were sometimes called Angels of Mercy. I spotted these (with real wings - well, almost real) at World Travel Market in London a few weeks ago. They, and the WW1 officers behind, were promoting battlefield tours in Belgium. I have no doubt that the soldiers who were injured or killed there would have been only too glad to go on a Battlefield Tour with a nice cosy hotel every night - rather than experience the real thing.
One thing that is nice, though, is the way these nurses are laughing and having a good time. Grandma got a lot out of being a nurse, and looked back with satisfaction on her time on the ambulance train.