From jonno946's link
quote
Note: While HTTP-EQUIV META tag appears to work properly with Netscape Navigator, other browsers may ignore them, and they are ignored by Web proxies, which are becoming more widespread. Use of the equivalent HTTP header, as supported by e.g. Apache server, is more reliable and is recommended wherever possible.
Which I'm happy to say confirmed my own suspicions about using META tags, which I never use. Now I don't have to worry that I'm missing something important. I suppose the point of them is to use them with browser detect and vary according to the result.