Whilst the Judges seem to have overthought this but so has El Reg
Bear in mind that afaik the Appeals court generally covers interpretation of LAW NOT interpretation of exact events. So arguments can quite quickly spiral off into theory land as happened here.
So from a laypersons perspective it seems to have been a bait and switch, the ruling was on whether it was right to have a infrastructure geared TEI based on the contents of RAM. To which this answer is a no brainer - well duh of course it was. So the judges ruling is valid.
If the method of interception WASN'T from ram, but OTA - then the method of collection was not legal - but even then this appeal ruling still stands, because that wasnt what was being challenged.
I have a feeling that the defence screwed up in the early trials and this was a late attempt at a correction. The defence at new trials should have the method of collection documented in detail and sworn to by an expert.
I also have a suspicion that the Rozzers/CPS are deliberately playing the "expert is a foreigner card" to game the evidence on the collection method. Besides which its Druggies, Paedo's and Organised Crime so its all good innit. (Sorry I sunk below the level of a Daily Heil reader for a miinute).