The JP Oxford Shirt.

I was looking for something both more and less than the traditional Oxford shirts I keep in regular rotation.

More expeditionary, something that would suggest military credentials. 

Less regimented, however. A less buttoned-up button up with enough good manners to be favored by upper-crust English sportsmen. It would also need to have an active-spirited style perfect for adventure.

Something that, with the right jacket and trousers, would still get me into Corrigans's Mayfair for lunch without raising any eyebrows. 

Looks like I've got the details worked out here. 

The JP Oxford Shirt (No. 7202). Inspired by a 1940s British officer's shirt with all the details you'd expect, including the extraordinary reinforced vintage style placket. Impeccably constructed from a specially-developed "modified" Oxford fabric using high-quality yarns, tightly woven to make it extremely hard-wearing, while the unfinished quality gives it a natural look. Button down, spread collar. Curved hem. Pleated chest pocket with military-style scalloped flap. Garment dyed and stone washed. Shell buttons. Contrast chest pocket button. Imported.