previous_post_link and next_post_link – exclude a POST

QUICK VERSION: How can i exclude a certain post (not category) when using previous_post_link and next_post_link ?

LONG VERSION:
I’m using previous_post_link and next_post_link to cycle through posts within a certain category or custom post type.

My problem is that I’ve used a post to add some text at the top of the archive.php so there’s some “intro” text above the list of posts within that CPT.

So when I use previous_post_link on single.php, it picks up this intro text post. So i want to exclude it from previous_post_link.

Any help greatly appreciated