Well, I have finally managed to baste all 31 pleats. I ended up with 5 setts across the back rather than the 4 I mentioned before. (My brain did not explode, but it looked for a while as though it might.) [Beware, this is much more time-consuming than pleating to the stripe!]

w2f nailed it when he said that the key is careful marking at the hip line. Measure and mark the pleats as if you were going to make a knife-pleat kilt. The only difference is that it has to be folded differently and each edge of the pleat extension (defined by your marks) has to be basted from top to bottom, not forgetting to taper from hip to waist, but not in the rise.

I used a card-stock pleat template to make sure each pleat was properly shaped. That is not as necessary if you pleat to the stripe as each bit is the same and after the first few, you can eyeball it. For pleating to the sett, you are using several bits of the sett and, for the solid colour blocks, extra chalk marks will be helpful.



Sewing the pleats will be next, but the rest of the project is quite straightforward.