A heavy overcoat. Mostly military, with a wide swath of double breast cover, so it would button close to left shoulder. I had one when I was in the army, just when they were half replaced with windbreakers. Near impossible to pack, being made of thickly woven material, it kept you really warm in winter.
Similar coats, often called the same, were used by any official services where personnel would have to work outside in the cold - post offices, railway personnel, factory guards.
13-V-2012 - 10-IX-2023