Hook size: Patten calls Size 11.5mm hook

From website:
This hot fashion item can be worked up in a weekend or a few evenings. Two strands held together and a giant hook make it quick and there is absolutely no finishing.

Sizes: Small (30-32 chest), Medium (34-36 chest), and Large (38-40 chest).

FINISHED MEASUREMENTS
sleeve width at top of arm 21 (22, 23)/53 (56, 58.5)cm
center back neck to cuff 29 1/2 (30 1/2, 31 1/2)/75 (77.5, 80)cm