I used to have a (British) Royal Navy greatcoat - no idea how old it was but the cut was generous, in that it had quite wide skirts even though the waist was narrow - about 28inches, though it was easily a 38 inch chest size. It saved my life in the damp climate of Portsmouth (Hampshire England) but I really can't remember what happened to it.

It had heavy shiny silver buttons - which were in an envelope in the inside pocket when I bought it, none of the other's had them, but they did not fit me.

The narrow waist helped with the weight, which was considerable in the rain - or even when it was dry. Wearing it unbuttoned was like carrying a back pack with all the weight on my shoulders. To button it up I had to lift my shoulders slightly, and then when I relaxed the skirt was partly suported.