Vintage Sisley Italy Size 44 fits like Small or Med navy blazer jacket back vent

Excellent used condition, navy blazer from Sisley. Please refer to measurements in photos as well as the size tag pictured in the final photo. This is marked as a size 44 IT - based on measurements, I estimate is fits like a size Small or Medium and have listed it as a Small. Extremely slight discolouration to back of interior collar (photo 5). Hard to capture as it is very faint. Items come from a smoke-free home :)