CO 210, to get one part-size up from S.
To avoid colour change on purl side after rib, worked a row of each colour in st st.
Have got 3 balls of Colourspun to 2 balls of the maroon Blacker, so am doing 4 rows maroon, 6 rows Blacker.

Buttonbands:

Did left-hand side first to get a feel for it. Worked out how many rows schematic had from length for my size, divided by number to pick up for band. Then worked out how many rows I had, which wasn’t far off what I was meant to. Used Knit Evenly app to calculate at what rate to pick up and knit (pu 5, skip next row).
BO with needle one size up.
Buttonhole side: dec given is a k2tog, this didn’t fit with my rib so did an odd p2tog so the RS had a neat rib still. Fiddly, but it is very neat.