My husband wanted a Carrick coat (think 18th c. highwayman's coat), and I thought it would be a good challenge. I started with Simplicity 4083, and made a number of changes to it to make it more similar to the historical coat John wanted. I also used it as an excuse to learn and apply more tailoring techniques, including fitting, lining, welt pockets, pressing, canvas structuring, roll line, and hanging the fabric with weights before constructing.
Here are some of the other things I adjusted:
a) Extended the height of the collar, added a stiff interfacing to keep the height and shape
b) narrowed and lapels
c) borrowed sleeve cuffs from Simplicity 4923
d) fully lined with a navy, paisley, jacquard
e) added pocket flaps to the back (historical detail)
f) added pleats on either side of the back kick pleat, with a button at the top (historical detail)
g) added double-welt + flap pockets on front
d) added a single welt pocket to interior
e) used tailoring techniques for shoulder pads, lapels, and body canvas including interlining, horsehair canvas, stay tape, and cotton batting
f) fully tailored to my husband
g) extended the length by about 8 inches
h) added a hanging loop at neck
Here is the Pinterest board I used for reference https://www.pinterest.com/carol_bales/carrick-reference.
About the welt pockets. I installed double-welt pockets with flap on the outside, and a single welt pocket on the inside lining. First I grabbed a pocket pattern from another Simplicity coat pattern and made a couple of practice pockets. Then I zeroed in on Alison Smith's Couture Tailoring:Construction Craftsy course, and Kenneth King's Pockets course. A few practice pockets later, I committed to installing them on the coat. Because the fabric frayes easily, and I figured that John was really going to load his pocketses with boy stuff, I extended the pocket bag so that it is also sewn into the side seam and the waist seam. I eventually found a very simple single welt seam technique on Youtube that I like also, and used it on the inside lining. It is mainly about practicing until you are comfortable, because there is really no going back if you mess it up.
Preventing the fabric from stretching out over time
This coat has a seam at the waistline, and since I added to the length, and added lining, I was afraid of the coat stretching out over time. I was also concerned about strain on the waist seam, and strain on the horizontal welt pockets. I ended up using a heavy cotton, almost canvas weight as interlining, and extended it past the waist line, reducing the pull on the woven fashion fabric. All fabric was hung with weights for several days to stretch it out. The pocket bag for the welt pockets was extended so that it was sewn in/secured at the waist, and the side seam.