One of the sub-editor's tricks is spotting when over-paid contributors have been burgling off the web.
Tip 1: If the writer's spelling switches from British to American English (or vice versa) for a whole paragraph, it's a good sign that something has been pasted from another source.
Being English, I'll stick to 'labour', 'centre' and 'arse' (no Oxford comma, as you'll notice), but it won't be a disaster for western civilisation if, in 50 years' time, the whole world has moved over to "labor", "center" and "ass".
If it happens, I'll miss the passing of 'arse' because the change of spelling seems to have created a subtle change of meaning. Of course, an ass is a kind of donkey as well as being an American backside, but the difference goes deeper than that. There's something about the 'r' that adds an extra coarseness to the spelling favoured in the British Isles. Just roll that 'r' around your tongue and feel the earthy crudeness of it. Arse. Arse. Arrrrrrrrrrrrrrrrrrrse. Listen to Father Jack. He's not saying 'ass'. He's saying 'arse'.
In England, you can call someone an 'ass', but that means you're comparing them to a donkey. It's also pronounced differently, rhyming with 'mass'. It's unusual to call someone an 'arse', though 'arsehole' is available and isn't much different in meaning to the American 'asshole'. The American 'ass' is more akin to the English 'bum', which seems to be missing in North America in terms of the human bottom.
Chaucer spelt it 'ers' in the 14th century, so that 'r' has a long history. An ass is cute. An arse isn't. And it was an ass that saw the angel.
Moral: If you want to be really crude, arse is the way to go.