From FibreMood:
Trench coats never go out of style. The oversize Martha pattern proves it's a true trench with charm and panache. You'll love the double breasted front, the belted waist and traditional rain flaps at the back and front. Thoughtful features like a back slit and welt pockets add an air of sophistication, while the shoulder lapels shout power!
In short, Martha will fit right into today's street scene.Fabric advice
There’s no trench coat fabric that tops gabardine. Gabardine is a tightly woven, smooth fabric with fine diagonal ribs. The fabric is so tightly woven that it’s almost impervious to rain. Gabardine fabric can be composed of wool or cotton thread or a blend of one of these with polyester or polyamide. Before you get started on the Martha, decide whether you want it to be a trend item, or a more functional raincoat.
Because...if you want to make a raincoat that's the real deal, you'll need raincoat fabric – obviously.