Template Layouts with closed entries 404 error page issue

So i have a template setup: /staff/index

which loads: /layouts/_main

I then have a normal entry which loads through /staff/john-smith All works fine…

I have then closed the entry “John Smith”. I expected this to then output my 404 template. But instead it outputs the layout with no content in the body area. The Header responds 200 OK.

I have tried adding various if statements with redirect 404. But these do not work outside the {exp:entries} tag, and when inside the tag it still loads the layout template, empty content, but headers show 404.

So what i would like to know - is with a closed article (but valid URL), how to i get my 404!!!

Thanks, N