I found the pattern (which has since had an invalid link on the pattern page) through the link on this forum post. I made the following changes (as I didn’t like all of the instructions in the pattern).

CO 40

Thumb: After picking up the stitches in the thumb hole, knit around in color B one round, then knit 4 rounds in color A, bind off

They turned out okay, but if I make these again, I will knit them in the round with the buttons and button band as purely decorative.
Button band:
Pick up 45 sts
R1: sl 1 purlwise, p across to last st, k1
R2: sl 1 purlwise, k across
R3: sl 1 purlwise, p3, bind off 2 purlwise, {p4, bind off 2 purlwise} across to the last 4 stitches, p3, k1
R4: sl 1 purlwise, k3, {co2, k5} across to the last 4 stitches, k4
R5: sl 1 purlwise, p across to last st, k1
Bind off