The correct method for constructing a tailored jacket is a matter of opinion.
Various methods of assembly have been used in the workshops of Savile row and elsewhere. It is rare to find two tailors who agree on one method, one order of construction.
More recent developments in technology has replaced the hand work, allowing for a speedier production time.
The following outlines briefly how a handcraft jacket is tailored, using minimal machine work.
Having mastered trouser making, a young apprentice would move into the realm of Jacket making. Before the jacket is finished, try-ons are carried to ensure a perfect fit. The number of try-ons used is up to the fitter. Typically a "Skeleton baste" is first. The foreparts are canvased and the jacket is basted together. At the second fitting the pockets are added, hence it's name, "Pocket baste". The next is the "Forward baste" when the facings are added and the jacket is unlined. The final fitting is known as the "Fit bar finish", this is where the garment is complete bar the buttonholes and hand finishing.
When the Jacket maker receives their work it is wrapped in a canvas bundle containing the trimmings by which it is made. All the pieces are trimmed at once, beginning with the body canvas with its haircloth and domette.
Combined they form the foundation on which the jacket is laid. It is common practice on Savile row to soak the canvas and the haircloth before drying, to shrink it fully. If the canvas was to shrink after the jacket is finished it would undoubtedly distort the fronts.
Before trimming the silesia and the lining, the jacket must be thoroughly thread marked. Care must be taken point to both layers of cloth. Darts and side-seams should be adequately thread marked to clearly define the run. The facing, pocket pieces and pocket bags are cut next.
Begin with chalking the facing, 4" wide at the hem and 2" past the shoulder point, cut with in a straight and gradual curve. Extra cloth can be allowed for at the in-breast, which should begin no less than 3" beyond the break line, finishing in the armhole. In-breast pockets are typically 5 3/4" x 6". Try to prevent the in-breast pockets from fouling the waist by positioning them high in the forepart. Inside ticket pockets should correspond with the outside flap pocket, providing support when sewn to it. As the lining is sewn to the facing it should follow a similar run. Use the facing as a guide when cutting lining and remember to added 1" to the edge to allow for the seam. The hem and side-seams are cut net, with 1" allowed around the armhole and 1 1/2" across the shoulder. The extra lining on the shoulders folds in a pleat in the chest. The lining darts correspond with the foreparts darts to give equal waist suppression.
The back lining is trimmed 1/2 " wider at side and 1 1/4" at the shoulder and neck.
The sleeve lining is usually white or another contrasting colour. 1" of inlay should be allowed on the top of the sleeve as shown in the picture above.
It's always better to machine the darts and seams in one sitting preparing for the next stage.
All seams and darts should be pressed open.
The canvases are basted together and then pad stitch to shape. The stitch proves a soft structure for the chest. The haircloth and domette which give the canvas its form are fulled into the chest area. When pressed the canvas is pressed the fullness is pushed out and along with the dart, proves the shape.
The foreparts are hand basted to the forepart. The cloth is gently stretched over the canvas, there are five rows of basting stitches that hold the canvas in position while the jacket is being made.
A lining strip is drawn off 1/2" over the break line and basted on. This is the bridle, it rpevents the jacket from lifting off the chest. The break line is then be pressed and shrunk.
The foreparts should be then pressed and the out-breast should now be added to the left side. Sewing the welt through the canvas prevents the pocket gaping with wear.