Download the pattern from sewmag.co.uk, then print and follow the cutting guide. With right sides together, pin the centreback seam and sew. Finish the seam edge with an overlocker, or trim and use a zig zag stitch. Press the seam towards the right. Finish the edges of the fly section and the centre-front seam using an overlocker or zig zag stitch. If using an overlocker, position up to the edge of the fabric, so that no fabric is cut away. Pin and sew the centrefront seam to the circle, right sides together, leaving the fly section open. Press the seam open.

Fold the left fly along the marked line and press. Position the zip so the pressed fold of fabric is close up to the teeth and the top of the zip is 2cm below the waist edge. Using a zipper foot, sew the zip in place very close to the fold. Fold the right fly along the marked line and press. Lap this fold over the zip on the left side, making sure that the stitching line is covered by the right fly. Pin the right side of the zip in place on the right fly; check that the zip is in the right place by opening and closing and making sure it is flat and level. Sew the right side of the zip to the right side of the fly just along the folded part of the fly section only, not through to the trouser front.

Close the zip and mark the stitching line for the topstitching along the right of the fly; this can be done with an erasable fabric marker pen. Draw the curve at the bottom of the fly and topstitch down from the waist edge, around the curve, pivot and sew back along the fold of the right fly for approximately 2cm. Make the pleats in the front trouser and stitch in place close to the edge of the waist to hold. Overlock or zig zag the bottom edge of each pocket. With right sides together, pin and sew the pocket to the front trouser along the curved edge taking a narrow 5mm seam. Clip the curve and press the pocket out away from the trouser front. Under-stitch the seam, turn the pocket to the wrong side and press. Topstitch around the pocket, close to the edge, then 5mm away from the edge.

Fold the pocket along the fold line towards the side seam and pin in place at the side seam and at the waist edge. Stitch across the bottom of the pocket. Sew the pocket to secure, close to the edge of the side seam and the waist edge within the seam allowance to keep them in place. With right sides together, matching notches and making sure that the centre-back and front seams are level, pin and sew the inner leg seam. Neaten the edge and press the seam towards the back. Pin the front to the back trouser at the side seam, right sides together, and stitch. Neaten the edge and press the seam towards the back.

Make the belt carriers by folding the belt carrier piece in half and pressing. Fold each raw edge to the centre and press again, then fold in half and press again. Sew down either side of the carrier. Cut the carrier into three equal pieces. Position one at the centre back and one at the edge of each pocket. Stitch in place at the waist edge to hold. Apply fusible interfacing to the wrong side of one waistband piece. Starting at the centre back and with right sides together, pin the waistband in position around the waist of the trouser over the edge of the carriers and sew. Trim the seam and press the seam upwards towards the top of the waistband.

Press the carriers up towards the top of the waistband and pin in place, then stitch close to the edge to hold. Overlock or zig zag stitch the bottom edge of the other waistband piece. With right sides together, pin and sew both waistbands together at the top over the top of the carriers. Trim the seam and any excess carrier. Under-stitch around the top of the waistband and press the edge. Fold the waistband at the right front edge level with the fly, right sides together, then pin and sew. Trim the seam and turn to the right side, pressing the edge.

With right sides together, fold the waistband at the left-front edge and mark approximately 3cm away from the edge of the left fly to allow for the button, then pin and sew. Trim the seam and turn to the right side, pressing the edge. Pin the inner waistband to the outer waistband along the seam and stitch in the ditch all the way around. Press the finished waistband. Make a buttonhole on the right side and sew on a corresponding button on the left. Try on the trousers and mark the position of the hem. Turn up the required amount and press the edge. Trim to 2.5cm if necessary and fold again to form a double hem, then stitch.