I ended up buying a circular 2.75 mm needle with a long cable so that I could start the two-at-a-time, toe-up, magic-loop technique socks and found a couple of instruction videos, first for JMCO from Knit Purl Hunter and another for Liat Gat's Limitless (long-tail) Cast On for two at a time, magic loop socks. I decided to go with the JMCO, since I learned how to do it on dpns and I like it better than a long-tail cast on (although I may use the latter if ever I get down to doing my legwarmers!). A few rows in, I started to wonder why magic loop is thought to be quicker than dpns. The idea is that there is less 'adjustment' of the yarn and needles, but I was finding getting the stitches from the cable back onto the needle to be an absolute pain, and using two balls of yarn, which needed to be kept on their respective sides, meant further fiddling about. After a couple more rows, I realised that the problem with remounting the stitches was that the joins between cable and needle tips weren't smooth. It's a Pony fixed circular, and just not up to the job of sliding stitches back and forth over the joins. I frogged the few rows I'd done, and started to wonder about how to smooth the join while I cast on another pair of cuff-down socks, from a pattern called 'Maidenhair Fern'.
I didn't realise from the picture, but this is an interlocking leaves lace pattern and doesn't look much like maidenhair fern to me, but I love leaves so it's not really an issue. I picked up the Drops Fabel 'Forest Long Print' (#650) which is a
self-striping yarn. I love the way it's made up of different colours
plied together, although it is a bit splitty and I'm not sure about the
bands of pale brown against the greens - the pattern would stand out more with a solid colour.
I usually need to cast on 72 on my usual 2.75 mm dpns in order to cope
with my chunky legs and ankles, so increasing to 75 sts for the pattern
repeats around the leg didn't seem outrageous (although I forgot about
how stretchy lace patterns can be). I prefer ankle socks, so did 12 rounds K2, P2 rib for the cuff, followed by 40 rounds for the leg, which was two and a half pattern repeats, achieved by starting on row 9 of the pattern.
The heel was worked over 2/5 rather than half the stitches, due to the multiple of 15 sts needed to continue the pattern down the instep. Probably because I was working on my own gauge and larger needles, the suggested heel flap seemed long so I only did 31 rows and picked up 19 sts along each side of the flap (including the corners to eliminate holes).
The increase to 81 sts for the foot after the gusset decreases seemed very strange - why have a larger foot than leg/ankle circumference? I decided to continue the gusset decreases until there were 20 sts for the sole and 45 for the instep pattern, leaving a total of 65 sts for the remainder of the foot, which was plenty.
The foot was 64 rounds (4 pattern repeats) from the start of working in the round again after the heel decreases to the start of the toe decreases, with the gusset decreases happening over the first 40 rows.