This is a pocket often used as the back pocket on mens' trousers although of course you can add one to whatever garment you wish... in this case I have used for the breast pocket on a mens' tailored shirt.
Measure and mark the position of the welt pocket. My welt pocket measures 13cm x 1.5 cm (5 1/8" x 5/8"). Cut two strips of fabric equal in length to the length of the welt pocket plus two seam allowances, and equal in width to twice the height of the double welt; in this case my strips measure 15cm x 3cm. Also cut a strip of fabric on the bias for the loop closure.
