The celebrated British stiff upper lip is just plain common sense

It was part of war; men died, more would die, that was past, and what mattered now was the business in hand; those who lived would get on with it. Whatever sorrow was felt, there was no point in talking or brooding about it, much less in making, for form’s sake, a parade of it. Better and healthier to forget it, and look to tomorrow.
The celebrated British stiff upper lip, the resolve to conceal emotion which is not only embarrassing and useless, but harmful, is just plain common sense.
George MacDonald Fraser, Quartered Safe Out Here: A Harrowing Tale of World War II