Create a separate author.php for our child themes

Thanks Tom. I'll have a play around and see if I can make a decent author page. I'll show you it when it's going.

Would integrating with ACF user fields be worth a look at?

ACF is pretty awesome. I wouldn't use it in an add-on just because it's the opposite of lightweight, but for a plugin or just working as a regular user it's great.

resolved