Sizing varies from model to model. We'd rather it did not, but fabrics behave differently when stitched up. That is why we post sizing for every item, not just have a general shirt sizing table. Any manufacturer/retailer who does do that is basically posting a "this is what we would like it to be" size chart......
I bought a couple of shirts (both the same tag size) from another brand recently, I had to go by their general shirt size table. One was way to small, the other marginally too large.
When comparing sizing measurements, make sure you do it in one place, IHUK, SE, RandH etc etc. Because there is variance how different retailers measure, so you need to be comparing apples with apples
