You will need 7 buttons. Rowan used gray plastic buttons.

Finished measurements:
Chest circumference: 35.5(39.75, 43.25, 47.75, 51.25)“ 90(101, 110, 121, 130) cm
Finished length: 19.75(20.5, 21.25, 22, 22.75)” 50(52, 54, 56, 58) cm
Sleeve to underarm: 17.75(17.75, 18, 18, 18) 45(45, 46, 46, 46) cm

Yarn used:
Rowan Denim Revive
Shade 216 Silt - 10(11, 12, 13, 14) balls