Has anyone done this before? I'd like the most recent comment to appear at the top of the page, reversing their order.

kind regards,
Rik

Some digging in the core files allowed me to find the function in the file zp-core/template-functions.php

here i edited the line:
function next_comment($desc=false)

and changed the code to true.

It is not recommended to hack core files. The option should be set on your theme files, that is why it is there.