Men's 40's Smoking Jacket/Coat Weldon

This a pretty cool vintage Weldon 'smoke coat' I found. It's in beautiful condition.....the only problem I find is there is no size tag on it. It measures approx. 22 inches across lying flat, so doubled would be 44. In a shirt of jacket that would be Large, right? But isn't a robe or smoke coat suppose to fit loosely? Would you say its more like a size Medium? Thanks for your help!