Adding a Zip to an In-seam Pocket

I decided to adapt McCall's 7512 so it fastens with a chunky exposed metal zip! Hence adding metal zips to the in-seam pockets seemed the right thing to do.
Follow my instructions for how to add an exposed zip to an in-seam pocket.
Use your preferred method to mark the position of the pocket. Do the same to the pocket bags.

Place the right side of the pocket bag to the right side of the garment, carefuly matching the pocket opening.
WS pocket
RS garment
You need to make a space wide enough for the width of the zip teeth you are using. Mark the fabric where you need to stitch.

I'm using a 1cm wide opening. Mark 1cm away from the seam line. The top and bottom of the pocket opening needs to be about 2mm away from the top and bottom of the zip teeth.
Machine from the cut edge, leave the needle in the fabric to turn a right angle. Stitch down the marked line, then turn to stitch back to the edge.
Trim the seam allowance to 5mm.
Snip diagonally into the corner, very close to the machine stitch.
Turn the pocket bag to the inside of the garment. and press. If you're using a fabric that's difficult to press like the one I used in my coat, understitch the opening, stitching through the pocket bag and the seam allowances.
PLace the zip behind the fabric. If you want to top stitch it, pin and using a zipper foot sew across the top, down the side and across the bottom.

However, if you don't want the stitching to show...............
WS garment
WS pocket
With the wrong side on top, open the pocket bag. Carefully pin the fabric to the zip tape, just onto the main fabric. Check the zip teeth are parellel with the edge of the opening when you fold the pocket back over the fabric.
Open the pocket bag, use a narrow toed zipper foot( I usually have these for sale in my shop) to stitch where you've pinned. Just the length of the pocket opening.
It'll look like this on the inside
....................and like this on the right side............                    
Place the second pocket bag exactly on top of the first, right sides together. Pin through both pockets, but not the body fabric.
WS pocket
Machine the pocket bags together. This is all you need to do if you're going to line the garment.
If the inside will show, use your favoured method to neaten the edges.

It's now time to join the two main body pieces together. On my coat that was the front panel to the side front.

Match the two pieces right sides together. Pin the whole seam. Use a narrow toed zipper foot to stitch the seam along the length of the pocket, keeping the edge of the fabric against the seam line.

Use your preferred machine foot, stitch the seam above and below the pocket, carefully overlapping the machining. Neaten the seam in an appropriate way for your fabric.. However, remember that when finished the seam will press away from the pocket.