This is a basic pattern which my sister, Nikki, wrote for me. It's also a good pattern to tweak and experiment with.
Using 2.75mm dpn's and sock yarn
Cast on 52sts reasonably loosely
Both left and right are the same...
On first round of k1, p1 rib, join into a round (13sts on each of the 4 needles) and continue for a couple of cms.
Then k 21 rounds
Start shaping for thumb...
Next round: M1, Place marker, k to end.
(M1 - using the left needle, lift the bar between the stitches from front to back, then knit this stitch through the back to twist it. It is possible to create a left or right slant to this new stitch)
Shaping Round 1: k to marker, slip marker, k to end
Shaping Round 2: M1, k to marker, M1, k to end
Repeat these two rounds until there are 21 (thumb) sts between the marker and the start of the round
Then: k 5 rounds (remember to leave the marker in place and just slip it when you reach it)
Next: Place the 21 thumb stitches onto a piece of waste yarn. Remove the marker.
Cast on 2 sts (the easiest way is to make loops onto the needle you have just finished knitting). These new sts will be part of the thumb. Then knit to the end of the round (54 sts)
Next k 21 rounds
Then work 4 rounds of k1, p1 rib. Then cast off reasonably loosely in rib.
Place the 21 sts onto 2 needles
Starting in the centre of the two cast on stitches pick up and k 3 sts then k 5 sts from needle (8 sts on Needle 1), k 10 sts onto needle 2, k 6 sts onto needle 3 then pick up and k 2 sts (8 sts on Needle 3) (26 sts on thumb)
Then: k 3 rounds
Work 4 rounds of k1, p1 rib then cast off in rib.