Based on the instructions from Kenneth King in his book Cool couture I made a sample of a welt pocket with flap. It really is just another method of making a welt pocket and attaching the flap after the basic construction of the welt. But I can't praise his instructions enough. They're well written, clear and mentioning how it must look like in the different steps, and sometimes what you could do wrong in a step. Some of the chapters in it were published earlier in Threads magazine, but as I only subscribe to Threads since about two years, I don't know whether these were all published before, and I didn't bother to check whether the book has more info on the chapters I've seen before or not. I don't care, I love the book. And he gives the measurements in metric equivalents too, which I find really helpful, as I never really get used to the inches (1/16, 5/8, 7/8, it's sounds so unlogical to me).
I started with the instruction for a welt with zipper underneath, and added the flap instead of a zipper. The basic idea is using a woven ribbon of the exact width of 7/8" (2,2 cm) which serves as interfacing and measurement. There I had to cheat, as I didn't have this width. Will be difficult to get this size too, as most ribbon in the metric sizes will be 2 cm. For my first samples I wanted to stick to the measurements of the instruction, so I cut this size from some woven waistband interfacing. It was evening and shops closed, no use even trying to get the right ribbon at that moment.
There are also marvellous instructions on how to avoid seam lines on the edge of the flap. I must try those someday, but as I now want a flap with a curve, this was not applicable.
I didn't make a picture of the first sample, which I made from thin muslin fabric. The second sample above is made with a flap too quickly sewn without drafting a proper pattern, so it's not even and a little too short. But I know how to do it now. Time to decide the length of the pockets and height of the flap and tab on the muslin waistband.
Recently Designdreamer asked which sewing machine I have. It's a Bernina Aurora 430, but for these welt pockets (not really necessary here, but I want to try piped welts too for another reason) I took my very old Elna machine, which I hardly use. This picture shows why. And if anyone has a solution for the Bernina, please let me know, my dealer didn't know one!
To finish the answers to two other questions:
Rachel asked for a way to get the Marfy pattern. In Threads it was mentioned as number 1666, and not published on the Marfy website. From the magazine: "To order send an email through the web site "contact us" page www.marfy.it .
NancyK: I won't make the open seam at the bottom of the leg. It makes this pair of pants even more special, but doesn't suit me. It would mean that the pants can only be worn with higher temperatures and after my legs have seen some sun.