Most of this site is hand coded (eg pure html & css written in the Atom editor). The CSS is built (hacked) on top of the excellent Bass Css by Brent Jackson. Previous iterations of this site were powered by Wordpress in whole or part, while the earliest may have used Flash or image map navigation (but I'm admitting to nothing).
Mike Barker 20.19 has been given its' own bespoke CMS written in PHP. More on that later.