The hat is worked in the mosaic slip stitch pattern, for which there is a tutorial included in Knitting Magazine 162.

Size
To fit head 51 cm to 56 cm circumference

Additional gauge
24 sts and 36 rows over slip stitch pattern, using bigger needles

Yarn
2 x 25g balls in 100 Milk
1 x 25g ball in 104 French
1 x 25g ball in 111 Boho
1 x 25g ball in 105 Pretty