You will need 6(6, 6, 7, 7, 7) buttons. Sirdar used their own buttons, # B5611-0785.

Finished measurements:
Chest circumference: 37(41.25, 45.25, 49.5, 53.25, 57.25)“ 94(105, 115, 125, 135, 145) cm
Finished length: 22(22.75, 23.75, 24.5, 25.25, 26)” 56(58, 60, 62, 64, 66) cm
Sleeve to underarm: 17.25(17.25, 17.75, 18, 18, 18)“ 44(44, 45, 46, 46, 46) cm

Yarn used:
Sirdar Country Classic DK
Shade - 8662 Dove Grey - 6(6, 6, 7, 7, 7) balls