My system preferences are set to British English, and the spell checker works well.
However, some of the ‘buttons’ on my version of Scrivener have American spellings; for example, ‘Center’, for ‘position of paper’ when in Compose mode.
This might seem finicky, and I’m not being pernickety to my American cousins, but does anyone know how to display a fully British English version of Scrivener?
Many thanks
The Welshman
There’s no way to do this - in general, if you look throughout the interface of OS X, you’ll find that American spellings are used: “Color”, “Center”, and so on. I can’t think of a single program UI that has been localised into British English, and certainly the main OS X UI hasn’t been. A British English version of Scrivener would therefore be incongruous with the rest of the system. In fact, an early version of Scrivener did use British English throughout the interface as standard (with no American English version available), but I ended up moving to American English for consistency. (I’m the developer, and I’m English, by the way.)
Besides, shouldn’t you be asking for a Welsh interface? 
Keith
Thank you for the rapid reply—flattered to get something from ‘the man himself.’
Thanks for the clarification and providing the reasoning, though a “British English version that is incongruous with the rest of the system,” does sound delicious!
I did have a Welsh version of another word processor. Problem was, it only ever wanted to write about rugby, or how it wanted to hook up with a Kernow version, and separate from the rest of the Operating System. 
Hwyl,
Iwan
Ha, those decentralised word processors! Hooking up with the Kernow version would be a mistake, though, as the drivers of the Kernow version are very slow and would hold up the whole system.
but not as much as the Microsoft Caravans do in the middle of summer 