Wellington of Canada vintage 'Viyella' plaid button up size 12... small

Viyella is the material it is made of. a combination of merino wool and cotton. bright tomato red coloured plaid. says size 12 on tag but not sure what that means in relation to this top... might be more of a mens size. I am usually a medium and this is too small. more like a ladies small. warm and breathable fabric. mother of pearl buttons. (some have chipped a little but not really noticeable from front of buttons. flawless construction.. only real signs of wear are on the MOP buttons and the label which is a little torn. there are no care instructions other than "wash as wool" so wash cold, dry flat ;)