VINTAGE IVY - University Stripe Button Down Oxford

Fantastic shirt with unusual fit

Let me state that this is a fantastic shirt. The cloth and shape are both wonderful. But the sizing is a little strange: I went with size 15.5 because of the listed neck and sleeve measurements, however the sleeves are a little long while the neck is a little small. I would usually go for a size 16 in shirts because that's the right neck size for me, but the 15.5 seems to have a 16in/40.5cm neck measurement. The 15.5 also has the correct neck to sleeve measurement for me, which is about 87cm. But after trying on the shirt, the neck feels like 15.5in! The sleeves are also possibly a little longer than listed. To go for a larger neck size I'd also have to get longer sleeves, but I need the sleeves to be shorter in which case I'd have to get a smaller neck size. In all, it's a lovely shirt but I'm confused at what body shape this is cut for, given the large chest, long sleeves, but narrow neck.