Showing comments to non members whilst hiding the comment form

Right, I’m pretty sure I’ve missed something really simple and rudimentary here, which is probably why I haven’t found a solution searching, so please bare with me and excuse my momentary bout of stupidity.
I’ve set up my site so that only members can comment on posts by checking the ‘users must be registered and logged in to comment’ radio button in the discussion settings on my sites back end, the thing is – whilst doing this removes the comment form from non members, it also stops them from being able to view any existing comments, and despite wanting to prevent non members from submitting comments, I would like them to be able to read the existing ones.
Have I missed a simple checkbox in the back end or is there a way that I can fix this by making an adjustment to my comments.php.

The sites at https://qphia.com
The following is an example of a post with comments (or not as the case may be) https://qphia.com/blog/2009/09/10/can-formalised-education-practices-act-t/

Any help or guidance is greatly appreciated.