Now I'm really confused. Under material the pattern states
Big Wool 100% Merino wool in the following shades
Yarn A, Black x 4 Rowan Siena 4 ply mercerised cotton
then it list the other colours.
Instructions start with the Yarn A for the front and back panels.
On the making up
After sewing together, a line of running stitches across the top to hold in place,. Using spiky Velcro fluff up the outer surface. Put the bag in washing machine at 40 with jeans or heavy fabric to help with felting.