I managed to open up the flap pocket on my new Tharpe - so I thought I'd post pics of it. I thought that they'd simply put the zipper and leather trim on top of a solid piece of leather that didn't have a slit for the pocket but I was wrong. The leather that is under the zip is not a part of the main body of the flap - instead it's a small piece sewn in by the innermost set of stitches that holds the zipper in place. It's old serves to cover that slit.
I used embroidery scissors and nail scissors to open the pocket.
First I pinched the fabric lining from the back so that it wouldn't get cut. It turns out there are two layers you need to pinch.
Then I folded the flap in half lengthwise and made a small snip barely through the leather. This shot was taken after but this is how I folded it.
Then you should be able to slip the tip of the scissors through and cut along the length of the zip. You can see the fabric lining the interior.
Pulling open the flap you can see the white liner and where the red leather strip was attached. The back of the leather strip is a little bit tacky with leather glue.
Comparison shot to the inside of the grey Tharpe flap