I thought this is his roundabout way of dealing with the royals supposed political neutrality 🤷‍♂️

I’ve heard it lots of times (sometimes just as “sixteen sixteen”) - mostly for years though.

And it seems like Wikipedia agrees:

In American usage, four-digit numbers are often named using multiples of “hundred” and combined with tens and ones: “eleven hundred three”, “twelve hundred twenty-five”, “forty-seven hundred forty-two”, or “ninety-nine hundred ninety-nine”.

https://en.wikipedia.org/wiki/English_numerals)

I don’t think e.g. Jane Austen was German.

You probably did, but then you did the sensible thing and (mostly) changed it around. You can read some 19th century novels and find stuff like “I am two and twenty years old”.

Mostly because it’s still the old order for the teens. 1616 could be read as sixteen hundred sixteen, right?