Sirdar Country Classic (50% Wool 50% acrylic, 50g/125m)
Yarn A Shade 0862 x 1 ball

Cygnet Pure Wool Superwash DK (100% wool, 50g/104m)
Yarn B Shade 2153 x 1 ball
Yarn C Shade 2999 x 1 ball
Yarn D Shade 2284 x 1 ball

If you want to make the headband in a single shade of blue/purple instead of 3, one 50g ball (104m) is sufficient for all sizes.

Child 16ins/41cm circumference
Adult small 17ins/43cm
Adult medium 19ins/48cm
Adult large 21ins/53cm
Adult extra large 23ins/58cm

Finished width 3ins/7.5cm