My striped 18th century not-a-polonaise with an en fourreau back as worn at Costume College in 2005. It was meant to be a polonaise, but I liked the look better without the back draped up. I'm wearing it over a shift, my first 18th century stays, two underpetticoats and a yellow linen petticoat. The cap is from the Kannik's Korner pattern and is made of Swiss organdy. The handkerchief is just a triangle of voile. The dress is from the Janet Arnold 1770-1780 polonaise pattern, altered to have the en fourreau back.
On the right, the matching pleats. I angled the fabric a little instead of using it on the straight of grain to get the V effect. For the back, I pleated it so only the striped part of the fabric showed.