The pattern calls for Rowan Yorkshire Tweed Aran, which has been discontinued. A suitable substitute would be Rowan Scottish Tweed Aran.

A woman’s aran pullover, shoulder fastened with buttons.

Shown in black (no. 414).

Requires 4 buttons (Rowan 00339).

From the book:

“The rugged Aran-inspired style of this knit is made delightful by the shoulder fastening and the lacy collar peeping out beneath the neckline.”