Complex sentence: This is presumably the band that Whitburn thought (as of the 1995 interview) could have recorded "Ready'n' Steady" in 1979; the band has stated that they did not record the song.
Split into simpler sentences: This is presumably the band that Whitburn thought (as of the 1995 interview) could have recorded "Ready'n' Steady" in 1979. However, Whitburn no longer seems to accept this possibility, and the band has stated that they did not record the song.