You will need 8 buttons. Rowan used # 9427224190 metal shank buttons from Groves and Banks in the UK.

Finished measurements:
Back width: 17.25(19.5, 21.75, 23.75, 26)“ 44(49.5, 55, 60.5, 66) cm Finished length: 23(23.5, 24.5, 25, 26)” 58.5(60, 62, 63.5, 66) cm
Sleeve length to armhole: 17.75(17.75, 18, 18, 18)“ 45(45, 46, 46, 46) cm

Yarn used:
Rowan Summerlite DK
A. Linen 460 - 8(9, 10, 11, 12) balls
B. Indigo 450 - 1 ball for all sizes
C, Black 464 - 1 ball for all sizes
D. Cantaloupe 456 - 1 ball for all sizes
E. Rouge 462 - 1 ball for all sizes
F. Khaki 461 - 1 ball for all sizes