Thanks. Mainly, the recording is a touch dull but it sounds better if you tweak the treble up. I didn't over-record it, so it can take this without distortion. The venue is a sports hall most of the time, with very little by way of soft furnishings or curtains to absorb reverberations, so you get a slightly "boxy" sound. The inevitable clapping is close to the mike but much less intrusive than you get on some audience recordings.
The Everly Brothers part lasts about 53 minutes but the odd thing is that they are followed by Ralph McTell on the cassette. Since he opened the show and since the first part of the cassette almost exactly fits 45 minutes, this makes me think that it may not be the original master cassette but a dub. When recording, I would usually flip a cassette well before Side One ran out. As I have hundreds and hundreds of cassettes, all in boxes in the garage, I'll have to see if I can locate a master recording. That alone may take a while.