Gather your supplies together, I used a yard and a half of 45" wide cotton fabric - pre-washed and ironed (1.5m x115cm wide fabric), elastic thread, normal thread and that 70's favourite ...ric-rac trim.
Cut the following pieces;
Dress body: 26" x 20" (66cm x 50cm) cut 2
Frill: 38" x 5" (96cm x 13cm) cut 2
Straps: 38" x 1" (96cm x 2.5cm) cut 2
Front placket trim: 8" x 1.5" (15cm x3.5cm) cut 1
Make the gathered ruffle for the bottom of the dress.
With right sides together, pin the frill to the dress piece, spacing the gathers evenly and securing the end threads of the gather in a knot to stop it 'de-gathering' (I think I've just made that word up....)
Sew the frill piece to the dress piece with a normal length straight stitch, taking care to keep the gathering stitches within the seam allowance, otherwise you will be able to see them from the right side of the dress. Neaten the raw edges to stop fraying (I used a zig zag stitch). Repeat for the other dress piece and frill.
With right sides together sew down one side seam. Press open the seam and neaten the raw edges. You should now have one large wide dress piece.
Shir the bodice of the dress using elastic thread.
With right sides together fold the dress in half and sew the remaining side seam, matching the hemmed top, ruffle seam and hemmed bottom.
turn your attention back to the bottom of the dress, which needs hemming.
Add the ric-rac trim to the bottom hem edge, I attached the trim from the wrong side with a straight stitch, so so it's just peeping out on the right side.
Take the placket piece and fold in half lengthways right sides together, sew making a point at the folded end and leaving top end open. Trim the edges and turn right sides out, poking the point out. Pin to the dress front as above, tucking the raw edges of the open end inside the placket. Top stitch around the placket.
Take the shoulder strap pieces and press a narrow hem along each long edge, then fold in half and press. Top stitch the open side, you can also fold the short raw edge under and stitch.
Stitch the shoulder straps to the dress, two at the front, two at the back.
All that remains is to add some decorative buttons to the placket,
Visit my blog post for a step by step tutorial including in-depth guide to the gathering and shirring techniques.