Why are they relying on FontLibrary's hamster in the first place? If you're going to use a weird font, surely the first thing you do is make a copy for your own hamster to, erm, nibble...
The proper commercial font libraries only give you a license and force you to use some sort of clunky Javascript that requires showing their hamsters your magic numbers every time your page loads and maybe they'll think about letting you see their beautiful fonts. Rehosting the fonts is verboten.
However, having investigated a bit further, fontlibrary.org isn't one of those - it's just a library you're meant to download from. And the AUK custom fonts *are* being rehosted on the AUK domain. The bit they're hot linking is this tiny bit of CSS:
https://fontlibrary.org/face/osp-dinWhich defines a font called DIN. Which isn't even used as far as I can tell...
You know what they say, pay six figures, get monkeys.
(at least it's no longer taking 90 seconds to load)