Place the upper inside pocket along the top edge of the lower inside pocket, making sure the right sides are together. Pin in place.
Lay the zip centrally along the seam line and mark the where the zip stopper and zip head are.
Sew along the seam line with a normal stitch length, but when you get to the first mark reverse a few stitches then increase the stitch length to the longest and sew up to the second mark.
Change the stitch length back to normal sew a couple of stitches, reverse back to the mark then carry on to the end of the seam. This allows for the longer basting stitches to hold the seam closed as the zip is inserted.
Press the seam open and flat and transfer the zip opening marks to the right side of the fabric.
Lay the zip face down on to the seam allowance making sure the zip teeth are directly on top of the seam. Pin in place and hand baste through all thicknesses of fabric to hold the zip in place. Make sure you sew across the ends of the zip at the marked zip opening to avoid hitting the zip stopper when sewing around the zip.
Attach the zip foot to your machine and make sure the needle is on the right of the foot. Starting just before a corner, sew clockwise around the zip 8mm from the seam of the zip. Pivot when you get to the end marks and turn the corner to sew across the zip. Keep going until you get back to the beginning and overlap your stitching slightly.
With a seam ripper or small scissors carefully undo the basting stitches and release the zip opening. You should have a beautifully centred zip now.
Fold under 1cm along each edge of the pocket. If you want to neaten the corners by mitering them you can follow the tutorial for the Simple Patch Pocket
Transfer the pocket placement line onto the bag lining. A quick and easy way of doing this is to fold over the top half of the bag pattern along the placement line. Lay this on top of the bag lining, you can clearly see the placement line but are still able to mark it onto the fabric.
Place the inside pocket so the top edge lines up with the placement line and pin in place.
Top-stitch around the edge of the inside pocket. You can sew a double row for decoration as well as to make sure the pocket remains strong.
Now we can finish putting the bag lining together.