In the UK music magazine Sounds, Tim Lott expressed his frustration with the album, saying, "Unfortunately, Octoberon is no major departure from (their) disappointing formula. But despite that, there are some fine, imaginative moments which point once again to the never-fulfilled potential." A review of the album, appearing in a January 1977 issue of Billboard magazine, said that Octoberon "has delivered an extremely accessible spacey-but-lyrical LP in the most popular style of Pink Floyd or Yes. There is nothing harsh or cultish about this music." In another mixed review, AllMusic's Paul Collins wrote that Octoberon lacks the harmonies evident in the band's earlier records, and that the album is "not up to the level of their best work, but worth a listen for fans."
(en.wikipedia.org/wiki/Octoberon)

Anybody who believes Barclay James Harvest were nothing more than polite progressive paragons should give this 1976 album a spin, because there’s depth, edge and humour here that delights and surprises.
The idea for the semi-mocking Polk Street Rag, for instance, came from the controversial movie Deep Throat, which you’d hardly expect to inspire such a band. But they tackle the subject with vigour. Ra is a dramatic piece based around the Egyptian sun god, borrowing a musical motif from Mahler. And May Day is a diatribe against political extremism and the bigotry it engenders – the track concludes with a choir singing six songs simultaneously, from Land Of Hope And Glory to The Red Flag and We’ll Meet Again. This brilliant device emphasises the confusion such views can sustain in the unwary.
Even the album title, which is a piss-take on Oberon, the Fairy King in A Midsummer Night’s Dream, underlines that there’s a lot more to the album than perhaps is clear at first glance.
(loudersound.com/reviews/barclay-james-harvest-octoberon-album-review)