David 99, Even though Zep was a Brit band, Atlantic Records was an American Company. The first US copys are the preferred closest to the Master tape copys. The UK pressings are NOT as good, even though this is a Brit band.
I have never seen a red/purple (1960s)Atlantic label on Zep 1 or 2. Usually the only way to tell on Zep 1 or 2 is to look at the inner sleeve where you will find all of Atlantic"s 1969 and 70 current releases. This is the only way. I don't remember any particular Mastering house marks on the inner label for you to look for. Anyway, one of the few times Mobile Fidelity did not botch up the Mastering was with Zep II. If you find a copy of that, grab it. I think it beats my original issue. "Thank You" was incredible on the MFSL version...........Frank