Update Nov 2023
The original Blacker wool used for the sample is now discontinued.
An alternative would be Blacker Swan 4ply, which is softer and fluffier so needles may need to be changed for correct tension.
Jamieson & Smith Shetland Supreme jumper weight looks good - but only comes in neutrals.
Try YarnSub.com for other alternatives.

Amendment Nov 2019
The Front shoulder stitches should be cast off and not left on a holder as stated in the pattern. The front and back shoulders should then be sewn together.

Inspired by classic tweed and fair-isle fabrics, the pattern has a slip-stitch pattern on the upper sections and simple fair-isle below.
The shoulders use the English tailored method, which sets the seams slightly back on the shoulders to give smooth shoulders and a pleasing fall at the back.