I've been re-reading Richard MacPhail's book; in the end it includes an interview with Steve which has a passage with Steve talking about songs that Genesis played live but never recorded:
Steve: "(...) I'd be quite happy if someone criticised 'Ghostliners' because we never did it with the band. We did it three times in Italy, we only played it live."
Richard: "It's such a good song."
Steve: "It goes places. There are two schools of thought. I know in Phil's book he criticises that and says that about songs like 'Across The River' but it's missing the point. It's a song that goes through many changes. It's prototype prog and we didn't know that what we were doing was prototype prog because there hadn't been a blueprint for it. It was a long tune. (...)"
What are these songs Steve is talking about? This interview with Steve is interesting but quite unstructured and I can't follow everything Steve says; right before the quoted passage he talks about his difficult relationship with Tony and Mike in the quartet period and how they would reject his ideas; after this passage he goes on to talk about King Crimson and how they used to link bits of songs in live versions. I'm not sure what period of time he is referring here to: still the quartet period, or did he jump back to the earlier years when he just arrived in the band?
By any means, I have never heard any other mention of songs called "Ghostliners" and "Across The River". Genesis performing unrecorded songs sounds rather like the earlier years, like when they would perform 'The Light', 'Twilight Alehouse' before its recording, 'Going Out To Get You' in its entirely changed-over live version or the pre-version of Can-Utility that was entitled 'Bye Bye Johnny' for some time. So maybe there was more of those obscure songs they performed but never recorded? Both Steve and Richard seem to have a clear memory of "Ghostliners", they don't even feel a need to clarify among themselves what they are referring to.
Also, I have no clue what passage in Phil's book Steve refers to. "Across The RIver"? I have been reading Phil's book at least twice and I cannot recall Phil mentioning a song named like this at all. Do I just have zero memory, or does Steve think Phil's book says something it doesn't? Can anyone clarify?