I took apart the original coat and here is what it looked like:
Here you can see how this ten-year-old coat fit before. The armholes felt tight. Neither center front nor center back closed to hang straight.
To address the tight fit in the armholes, I enlarged added 1/4 inch to the width & length of each side of bodice front, each side of bodice back and the sleeve. The width affects the entire bodice - it is cut through the vertical darts.
To make center front and center back hang straight, the vertical darts were let out:
To provide additional wearing ease, the side seams were increased:
I sewed a muslin to double-check the fit and scheduled a fitting just before the lining was installed.
Voila, a new coat:
I am participating in the "Jacket-A-Month Sewalong" and this counts as jacket #1.
And, I am keeping this pattern! With a shoulder alteration, this pattern fits me, too.
There were a few shortcuts - I just followed the manufacturer's construction techniques. There are no buttonholes in the pocket flaps, no sleeve-head and the only stabilization was block-fusing all of the fabric and a narrow twill tape sewn on the front edges of the facing.
Overall, about as easy as a coat can be. Time-consuming, yes it goes without saying - but not difficult.
(now I want one!)