Place the front pockets right sides down onto the right sides of the trouser fronts matching up the balance marks. Sew with a 1cm seam allowance.
Press the pocket bag away from the trousers and under stitch through the pocket and seam allowance to prevent the pocket from rolling back.
Do the same to attached the back trouser pockets to the back trousers. We then neatened our seams to prevent fraying.