The jumper is crocheted bottom upwards, in the round up to the armholes. From then on, the front and back are crocheted separately in rows.
The three-quarter length sleeves are crocheted out from both the front and back sections. Finally, the jumper is crocheted together at the shoulders and on the sleeves (the pattern off-sets itself by half a pattern repeat on every round of the body, but this is not seen when the jumper is finished).

The small size will fit bust 30-32 in, medium 34-36 in and large 38-40 in.

Stitch markers (particularly lockable ones) will be advantageous, and less than one ball of the Duo is needed to work a slip-stitch around the cuffs and waistband and a small portion of the neckband.