After a few tests, I\'m starting to reach the conclusion that a browser does not send a Referer HTTP header when one clicks to a http page from a https one.
What sec
The HTTP RFC states, in section 15.1.3 Encoding Sensitive Information in URI's :
Clients SHOULD NOT include a Referer header field in a (non-secure) HTTP request if the referring page was transferred with a secure protocol.
So, this is expected / standard behaviour.