Cast 60 stitches onto a single needle. Distribute stitches evenly across 3 needles. Join, being careful not to twist.
Work 15 cm/6 inches of K3 P1 ribbing, as follows:
Round 1: *K3, p1; repeat from * to end of round. Repeat this for every round.
This portion is worked flat in plain stocking stitch.
Knit first 27 stitches. Put remaining 33 stitches onto a holder. Starting with a purl row, work 21 rows of stocking stitch, slipping the first stitch of every row. The right side is facing for next row.
RS: Knit 18 stitches, SKP, turn
WS: Slip 1, purl 9 stitches, p2tog, turn
RS: Slip 1, knit 9 stitches, SKP, turn
Repeat last two rows until all stitches have been worked. Ensure right side is facing for next row. 11 stitches remain on the needle.
Re-establish Round and Create Gusset:
Knit all heel stitches. Using that same needle, pick up and knit 15 stitches along selvedge edge at side of heel, using slipped stitches as a guide. With a new needle, work in pattern across the 33 stitches of instep – those stitches that you’d set aside on the stitch holder. Using another new needle, pick up and knit 15 stitches along selvedge edge at other side of heel, using slipped stitches as a guide. Work 6 stitches from the first needle.
The beginning of the round is now at the centre of the heel. There should be 20 stitches on the first needle, the 33 stitches of the instep on the second, and 21 on the third. Rearrange the stitches if you need to.
From here on in, the 33 instep stitches will be worked in the rib pattern, and the gusset and sole will be worked in stocking stitch – that is, knitting every round.