Sorry in advance if it's considered taboo to bump old threads here. All the threads on the first page in this particular board look old though. (Also sorry for the MASSIVE wall of text I typed up...didn't expect to explain their whole history, but since they're such an obscure band, I figured I should.)
Anyway, OP, I made an account to thank you for making this thread. Hypnosis of Birds is my favorite album of all time, and it makes me glad when I see other people talk about it, as it's such an obscure work. I find it hard to put the album's style into words because it's sooo unique, but "Voivod meets Joy Division" is probably my preferred way of putting it. Though "avant-garde post-punk voivod prog goth hybrid" and "Joy Division / Fudge Tunnel by way of Jethro Tull / Cynic" are pretty good ways of putting it, haha. I think that's why it's my favorite album; nothing else combines moods, textures, and styles quite like it, and still comes across so cohesive too.
However, it's not quite their "second" album. If we're not strictly counting studio works, 1982's Live: Hot Curry and Wine could count I think, since it has a fair bit of new material. That new material fucking smokes by the way; Forcedown Breakdown has some definite proto-thrash vibes, and of course The Small Hours gave the band quite a bit of fame by way of Metallica's own $5.98 EP. If we are exclusively counting studio works, there's No Man's Land, although that is Holocaust's worst album, for reasons I'll get into in a bit. After No Man's Land, there's The Sound of Souls, a five-track EP that fucking RIPS, at least if you like Voivod, which I very very much do. It's a nice slab of progressive thrash metal, and I mean progressive: check the nearly 12-minute closing track, Three Ways to Die, or the mostly-instrumental track Curious right before that, which has about four or five different beat/tempo/time signature switch-ups in the space of like one minute.
So why did they suddenly go prog after No Man's Land? Time for a bit of Holocaust history, but without anything to do with Nazis or Jews. See, the main songwriter and lead (?) guitarist of the band in their most known years was one John Mortimer. John Mortimer wanted to take their sound in a more metallic, heavy direction, while the rest of the band wanted a more mainstream, hard rock direction. You can see Mortimer's vision in the form of the faster, heavier new tracks on Live: Hot Curry and Wine. It's my belief that if they'd have recorded a full second album including those tracks, it would've been Holocaust's most-known album and would've made Holocaust an even bigger influence on the thrash scene. Instead, the rest of the band split off into the vastly inferior group Hologram, who released one album and died quickly.
John Mortimer, however, retained the Holocaust name, and recorded the second proper Holocaust album No Man's Land in 1984 on a shoestring budget almost entirely by himself, with only the drums done by someone else, one Steve Cowen (who would go on to play on all their best albums). John Mortimer had to produce it by himself, again for dirt cheap, so the sound quality is bad and thus strongly nerfs the enjoyment of the songs. He also took over lead vocals for the band for the first time, and was not a good singer at all on that first release, further hurting the songs. And it's unfortunate, because there are good riffs and ideas on there; some tracks could've been damn good if well-recorded and with Mortimer bringing much better vocal performances!
The album absolutely bombed, of course, and thus both groups of Holocaust went out on a dud...for a time. As we know, Metallica covered The Small Hours on Garage Days Re-Revisited, and the royalties from this allowed John Mortimer to revive the Holocaust project...the band, not the mass genocide. John Mortimer got way into Voivod, Kreator, and Celtic Frost, as evidenced by the roaring comeback EP The Sound of Souls, by far the best thing released in the Holocaust name by that point. It is certainly a heavy fucking album, the heaviest Holocaust would ever do. Yet it was followed in 1992 by Hypnosis of Birds (which would be the third full studio album; again counting Hot Curry & Wine and The Sound of Souls, their fifth.), their softest and most introspective. Mortimer (who was by this point doing pretty much all the songwriting) kept the Voivod influence but threw in a bunch of new-wave and post-punk for good measure.
Their adventures in progressive metal continued after Hypnosis of Birds, in case you're curious their later work. 1997's Covenant is very much a prog metal album, and although the really eccentric influences of Hypnosis of Birds are mostly undetectable, it is a really creative, well-done album. After that, 2000's The Courage to Be is another well-done album, in my opinion their second weirdest; the avant-garde stuff came back in shows itself in tracks like Spanner Omlette, and other songs like When Penelope Dreams recall the highly creative melancholy of Hypnosis of Birds. They tried to get back to a "heavier" sound with Primal, and while some of the riffs indeed go hard and there are unexpected gloomy shoegaze-y parts deeply hidden within, it's a little boring, especially when you put it next to their best work. Mortimer's three-piece Holocaust went on hiatus for about ten years after Primal. They released Predator in 2015, which sounds like a typical NWOBHM comeback album...for the most part. There are some tasty riffs in many tracks, and a scant couple surprisingly progressive moments, but in general it's quite conventional. However, they released a new album just last month, called Elder Gods, and while it's certainly not up to the incredibly high standards of Hypnosis of Birds, it does bring a melancholic, progressive sound back to Holocaust, and sounds quite inspired, even if it has that "old metal band making new music again" type production to it.
So that's Holocaust, a NWOBHM band with an amazingly unique career path. Hypnosis of Birds is essential listening! The Sound of Souls, Covenant, and The Courage to Be are fire too.