I decided I wanted to be able to log in and post from outside my home network, and using vanilla http to do that while running on unencrypted wifi at the coffee shop was just asking for trouble.
Thankfully, Let’s Encrypt has made setting up https on your site both easy and, more importantly, free!
The “wonders” of how my old install of WP was set up has meant that older posts may still have bogus links in them, but on the front page (and going forward) at least, you now see:
Woot!