Wow, Bob. Thanks for that! It certainly cleared up a lot for me.

It's funny that in some countries a commonly used word is archaic in others. This has been brought up quite a bit in this thread. Now we have another!

who then pours it into one or more flagons (yes, that's the word, otherwise archaic)

I looked up the definition of flagon on Atomica and, I have to say, I had never heard of that ecclesiastical definition before.

A flagon is quite a common term here and, probably, in Britain too (we having adopted it over time). However, its common use is as a defining measurement of bottles of spirits. A flagon is a half bottle and a nagon a quarter bottle. (Don't ask me where nagon came from!).

Presumably these terms were adopted from the ecclesiastical ritual of mixing water and wine in 'equal' proportions to make a sum total (I do remember from my church going days that some older priests leaned more towards the wine and added only a few drops of water to their spiritual tipple).