Swags and tails were usually found in grand houses and hotels but are becoming more popular in homes where a more formal treatment is required.
Like pelmets and valances, swags and tails need to be in proportion to the rest of the window treatment with the swags approximately 1/6th of the length and the tails between 1/3rd and 2/3rds the length of the curtains.
Making swags and tails is a time consuming exercise which needs a lot of patience and is not suitable for an inexperienced sewer. It is essential to make a swag and tail from a spare piece of fabric to ensure the right size and effect is achieved.
A swag is a shape of fabric which is pleated, draped and fixed to a pelmet board. Two or more swags can be made to fit across the width of the pelmet board and can overlap each other or butt together with ornate tails in between as well as at each end.
Tails overlap the end swags to finish the treatment and conceal the sides of the pelmet board. These are pleated so that the lining shows from the right side and therefore need to be backed in a contrasting or co-ordinating fabric.
These instructions are for simple lined swags and tails which are pinned to the top of the pelmet board individually. They are cut on the straight of grain which, in my experience, make them easier to work with.

Preparation:

Firstly make a decision on your fabric. Avoid heavyweight fabrics that have either a nap (pile) such as velvet. Checks and stripes make matching patterns much more difficult.

Decide on the number of swags and if they are to overlap or butt against one another. The overlap distance is usually between 4" and 6" (10 - 15 cms). An even number of swags must be fitted in a running style but an uneven number can be fitted with a centre swag.

Print these instructions, including the detailed views of the illustrations. Read them through thoroughly making sure that you understand all the terminology used.

Measuring:

Fix a pelmet or cornice board above the curtain track 8" (20 cms) longer than the curtain track.

Mark a pencil line along the top of the pelmet board 1" (2.5 cms) in from the front and end edges.

Along this pencil line mark the position of each side of each swag.

Drape a piece of string from one swag side position on the pencil line to the other swag side position with the centre of the string at the finished length of the swag.

Measure the length of the string.

From these measurements you can make your paper pattern for your swags.

Making a paper pattern:

On a large sheet of paper mark a line equal to the width of the finished swag across the top (A). Measure in 2" (5 cms) from each end and mark (G). Mark the centre point.

From the centre mark measure 2½ times the finished length (drop) of the swag and mark (B).

From this point mark the length of the piece of string and draw a line (C).

At each end of (C) measure up a distance of 2½" (6 cms) and mark (D).

Draw a curve from points (D) through the centre point of (C).

Cut out this shape (the red lined area of the diagram) for your swag pattern.

Positioning the pleats: mark a distance 2" (5 cms) down the side from line (A), do this on both sides (E).
Mark a distance 2" (5 cms) up from point (D), do this on both sides (F).
Divide the distance between (E) and (F) along the side edge into equal amounts of approximately 4" (10 cms), do this on both sides.
See the detailed illustration for further clarification.

Your paper pattern is now ready for use.

Cut out a swag pattern on a spare piece of fabric and follow the making swags section as a trial, there is no need to neaten the edges on this trial version. This is essential as adjustments can be made if necessary to achieve the desired effect.

Making the swags:

Cut out 1 piece of fabric from your paper pattern for each swag adding ½" (13 mm) to all edges for seams. Join widths of fabric, if necessary, using a flat seam and matching pattern where appropriate.

Cut out 1 piece of lining from your paper pattern for each swag adding ½" (13 mm) to all edges for seams and using a fabric pen mark the position of the pleats on the sides and top edges.

Place fabric and lining, right sides together, pin and sew around all four sides ½" (13 mm) in from the raw edges leaving an opening of approximately 6" (15 cms) at top edge for turning.

Clip seam allowance on curved edges and turn right side out.

Turn in seam allowance on the opening, slipstitch and press.

Pleat swag by folding the sides so that each pleat mark, (E), (E1), (E2), (E3) and (F) coincides with the 2" (5 cms) pleat mark on the top edge (G). Pin the pleats on top of each other keeping the top edge straight. When the whole side is pleated the bottom corner (D) should be on top of the top corner (H).
To make this easier pin the top edge of your swag onto the side of an ironing board so that the swag can hang down while you pleat each side.

Pin swag onto pelmet board with top edge on the pencil line. Adjust pleats if necessary to give the desired effect. Mark any adjustments you make onto your paper pattern.

When you have reached your desired effect remove the swag from the pelmet board and stitch the pleats in place. This will have to be backstitched by hand because the number of thicknesses of fabric will normally not go through a sewing machine.

Repeat steps 3 to 8 for all your other swags. Pin them onto the marks on the top of the pelmet board.