British vs. US English

There are many comments and writings that have been made about the differences between UK and US English. However, an interesting thing came across my news-ticker: UK archaeologists discover Roman armor. This was not the surprising thing (although as far as I know, the finding is momentous for many reasons, including that a complete set of Roman armor had not previously been found -- to the best of my knowledge). What was surprising (to me) is that the entire copy following the title (which spells armor the US way; with the "or" instead of the "our" ending) was written in British English (indeed, the first sentence reads, "Cardiff University archaeologists excavating at the Roman Fortress in Caerleon, South Wales have discovered what they believe is a complete suit of Roman armour." Huh? Why didn't the editor of this Cardiff-University-prepared piece not just go through and change the UK into US English, or just change the "armor" in the title to "armour"?

Other words which are British (or more common in UK usage):

• penultimate (uncommon in the US)
• artefact (spelled artifact in the US)
• barrack (more often encountered as barracks in the US)
• monumental (in the US it often refers directly to monuments, not to the size of a building)

At least Dr. Guest -- the one interviewed in the story -- appears to be from the UK, and isn't a US English speaker, which (if he were) would make his direct quotes not conform structurally to his dialect. It would be kinda ironic if he were, though, since I am a proponent of using UK spellings when referring to UK things (or in quotes given by UK speakers), and the same for US spellings.