Hi, I'm attempting to replicate this frock coat, but the pleats/skirt is confusing to pattern. I can't quite tell how the bottom of the skirt is cut so that it can be pressed to make pleats, how might I go about this?
What era is the coat? A number of historical pattern drafting books are available that show how tailors approached this problem at different times.
In brief and to over-generalize: Earlier coats had deeper pleats, which might be uniform width from waist to hem, or tapered. By the time frock coats fell out of fashion after WWI, pleats were quite small or even false, and generally tapered to the bottom.
For all periods, the pleat is cut with the main skirt piece, and folded under. The back skirt piece (cut as part of the back) allows for the width of the pleat below the waist seam. So the back piece has a notch or hook shaped extension in width above the waist, and the finished pleat lines up with the curved seam on the back of the coat.
Hope this helps,