Did a bit more searching and found the following link. Quite a lot of the links to downloads are now broken and don't work, but if you look under the Blue For You tour then there is an active link to the Cardiff gig:
The Cardiff boot is about the quality I would expect from that era.
Oh, and the 1973 Dublin National Stadium gig is on there too, which contains an insane 26 minute version of Is It Really Me?/Gotta Go Home which easily compares with the aforementioned Stockholm version.