Using wool yarn from stash, from Finland. I thought it was fingering weight, but seems slightly thicker, and does have a bit of a halo.
Reduced total number of stitches to 80 around mitten to achieve size to fit me with the yarn I have.
The book shows 90 stitches around the mitten pattern.
My mitten is not lined. It fits my med/lg woman’s hand.

72 stitches around mitten in garter stitch cuff. Increased to 80 stitches around mitten in black and white colorwork section.
The gauge of the garter stitch type edging on cuff is wider than the same number of stitches in stockinette stitch colorwork.

Size 0 needles used for garter cuff/edge, size 1 for colorwork.

I used 2 stitches between decreases on the top edge of mitten tip and on the tip of the thumb. e.g.: back side of hand: k1, ssk, knit in pattern to last 3 sts, k2tog, k1.
Palm side is same, with 1 edge stitch before (or after) decrease. All edge stitches and decrease stitches are worked in white yarn.

Due to change in gauge, there are fewer total rows in this mitten than in the chart.

The inside thumb pattern is a k1 black, k1white pattern with alternating colors on the next row.