You will need one button. Rowan used #1470 from Bedecked in the UK.

Finished measurements:
Bust circumference: 40.25(44.25, 48.25, 52.25, 56)“ 102.5, 112.5, 122.5, 132.5, 142.5) cm
Finished length: 30.75(31.5, 32.25, 33, 33.75)” 78(80, 82, 84, 86) cm
Sleeve length to underarm: 17.75(17.75, 18, 18, 18)“ 45(45, 46, 46, 46) cm

Yarn used:
Rowan Felted Tweed
Shade 151 Bilberry - 8(9, 10, 11, 12) balls