He has just come from the tropics, for his face is dark, and that is not the natural tint of his skin, for his wrists are fair.

He has undergone hardship and sickness, as his haggard face says clearly.

His left arm has been injured.

He holds it in a stiff and unnatural manner.

Where in the tropics could an English army doctor have seen much hardship and got his arm wounded?
Clearly in Afghanistan.' The whole train of thought did not occupy a second.