You will need 7 buttons. Rowan used #BN1979 from Bedecked in the UK.

Finished measurements:
Chest circumference: 36.5(40.25, 44.25, 48.25, 52.25)“ 92.5(102.5, 112.5, 122.5, 132.5) cm
Finished length: 20.5(21.75, 22, 22.75, 23.5)” 52(54, 56, 58, 60) cm
Sleeve to underarm: 17.75(17.75, 18, 18, 18)“ 45(45, 46, 46, 46) cm

Yarn used:
Rowan Valley Tweed
A. 101 Malham - 5(5, 6, 6, 7) hanks
B. 119 Curlew - 1 hank
C. 113 Marsh Orchid - 1 hank
D. 108 Hardrow - 1 hand
E. 118 Bell Busk - 1 hank