Update from the Knit Rowan website:
Knit this ladies accessory cable poncho, a design from the Rowan archive that is now available as a free pattern to download. Designed by Grace Melville using our wonderfully soft yarn Big Wool (wool), this poncho has deep rib edgings and a chunky rib stand up collar.

Finished side to side sleeveless width dimensions:
118: 149 cm
46½: 58½ inches

Yarn Information:
Photographed in Steel Blue 052
13, 16 skeins
1131, 1392 yards

Can also be knitted using Rowan Big Wool Colour