[mike-cardwell]

I've been using "no-referrer" rather than "none" as per https://w3c.github.io/webappsec-referrer-policy/ which is linked to from the "caniuse.com" link you quoted above. Am I wrong?

[davecardwell]

It looks like there was a change on 19th August, 2014: https://github.com/w3c/webappsec/commit/b48b635f93a798da87c6...

However, clicking the link to “Latest Version” at the top of the document you linked (from Dec 2015) takes you to the document I posted (from Aug 2014) so…who knows? It will require some testing to see what the browsers have actually implemented I guess.