Titting about Kensington had to turn serious sometime. But not quite yet. Their self-titled first album had fared badly in the charts and was described by Nick Kent as "a bucket of urine", but Queen still had a maniacal belief that there was room for their music in an industry that recoiled at the feathery sight of them. The gap between how they saw themselves and how everyone else saw them was never wider than at the time of Queen II's release in March 1974 - and this was three years before the NME's Tony Parsons' feature on Freddie Mercury, which ran with the headline, "Is This Man A Prat?" So the popular consensus on their performative exuberance and sludgy music was less than ecstatic, and the number of those who did get it was depressingly small. Reflecting on the period at the end of '74, Mercury told the Melody Maker about his band's failure to be a headline act: "Being support is one of the most traumatic experiences of my life." 

Queen were not built for second place. 

Indeed, Queen II was the last time the band would be runners-up in pop. They followed it up with Sheer Heart Attack, which had 'Killer Queen' on it, setting into motion the widely documented rise, rise and further rise of Queen. But Queen II, by virtue of the band's incurably experimental tendencies, was a spectacle in the De Mille sense of the word. Everywhere your ears look, there's a sound you can't explain. The capabilities of Trident Studios and game producer Roy Thomas Baker were strangled, massacred and ruthlessly left for dead, the stereo effects whooshing past without a care for how stretched it made the overall sound. Queen had bigger experiments on later albums, but never had they or would they over-extended themselves as much as this in relation to the technology available, and rarely with such satisfying results. It is myth, it is opera; it is a contest of bravado and a constant display of dashed-off genius.

With its simple structure of a Side White and Side Black on the original vinyl pressing, the record pits Brian May's and Freddie Mercury's songwriting directly against one another. Competition between the two must have been aggressive: because both sides show their respective songwriters to be desperate for immediate impact. May's Side White begins with the ominous thud of Roger Taylor's bass drum before his stately guitar arrives through John Deacon's specially modified bass amp, unable to contain itself in the studio and prefiguring the sonic madness that was to follow. 

Emblematic of that madness is the colossal 'Father To Son', which sees May's natural anthemic talents at their best and his guitar become a colossal-sounding prefigure to the NWOBHM (he and the whole record remains perhaps one of the stealthiest influences on the genre). It's gleefully monolithic in its climactic sections, but the words have an unfaltering belief that mere rock music is a strong enough medium to impart words of familial wisdom through the generations. That's why it succeeds - Queen's conviction would never be stronger. 

After a mournful interlude of 'White Queen (As It Began)' and the surprisingly breezy (given the general doom-mongering that characterises the album's opening) 'Some Day One Day', it's unfortunate to then experience the album's one major faltering. The only track that could be removed to improve Queen II and make it thrive stronger is Roger Taylor's tacked-on contribution to the end of the first side, 'Loser In The End'. It's a clod-headed strut at best, with lyrics about how it's important to be nice to your mum (this isn't even a pithy joke. That's literally what it's about). Which is kind-of ridiculous, given that 'Father To Son' had already set out the record's stall in terms of Homeric familial platitudes. Whether its inclusion was a token gesture to Taylor or the band genuinely thought its place was deserved amongst the wall-to-wall references to mythology and obscure art, or even if they laboured under the troubled belief that this was going to be a second chance at having a massive single from the album (after 'Seven Seas Of Rhye', included for that purpose alone), it's one of the worst things the band ever recorded. Don't skip it every time, is my advice. But definitely most times.

That Side White ends on such a shit song emphasises exactly what is so alluring about the competition happening on Queen II. Mercury's Side Black begins with a shrill, choral smash of altimeter-smashing intensity, a complex, unbalanced chord that jars and never resolves. It's clear. Side one, guitar; side two, vocals. 'Ogre Battle' does rely on May's guitar in its heavier sections, but Mercury's writing is far more harmonically sophisticated and, though by this point it seems impossible, higher-concept. Fiery beams are launched from the ends of guitars and drumsticks at fire-breathing, baby-eating bipeds, backwards gongs slosh the sound to even more extreme levels of discomfort, and Mercury emerges as the true victor. Bloodied he may be, but he has a smile on his face throughout.

If 'Ogre Battle' tried the patience of anyone hoping for more evidence of Queen's roots in three-minute pop belters, 'The Fairy Feller's Master Stroke' is the time to turn and run. Inspired by Richard Dadd's Breughel-esque painting of the same name, the hilariously gay title would lead most to assume this is an early example of Mercury's sexuality shining through, one of those things pundits roll their eyes at years later, saying "I can't believe no-one twigged!" But it's much straighter than that (no pun intended). Mercury was obsessed with the original painting and its multi-faceted business, so the song naturally exudes similar traits in the shape of harpshichord solos, Mercury's most piercing use of falsetto and a forensically exhaustive description of the painting's various scenes. In conjunction with the following 'Nevermore', which it seamlessly segues into, and 'The March Of The Black Queen', 'Ogre Battle' kicks off Queen II's defining streak.

Too complex even for Queen to play live in its entirety, 'The March Of The Black Queen' is the band's willful, pre-stardom difficulty summed up neatly in six minutes. While 'Bohemian Rhapsody' ticks a lot of the same boxes in purely formal terms (length, episodic construction etc), this song is more petulant and less ready to accept the strictures of pop. It's easy to forget that Freddie Mercury was, before he ever became a pop star, preternaturally attracted to the drama of opera. So when he shrieks, "I'm Queen of the Night!", it's not a reference to the momentum-gathering debate on his sexuality – it's him jostling with Mozart's The Magic Flute. Opera was to figure heavily throughout Mercury's songwriting as Queen's career went on (the middle section of 'Bohemian Rhapsody', the Verdi quote at the beginning of 'It's A Hard Life', the whole of the Flash Gordon soundtrack, his eventual collaboration with Montserrat Caballé), but this is Mercury's appreciation of opera in its rawest form, with aria-like sketches and snatches of character-pieces nestling beside one another as Mercury gamely and schizophrenically takes on all roles.

Nipping past the Zeppelin-esque balladry of 'Funny How Love Is' leaves us with only 'Seven Seas Of Rhye' to go. But by this point, the meat course is well and truly over. Side Black, perhaps by virtue of being heard second, has fairly trounced Side White. 'Seven Seas Of Rhye' does feel completely separate to the rest of Mercury's half of the album (much like 'The Loser In The End'), and is one of the very first times that Queen acknowledged pop's immediacy. Numerous quotes from the band confirm that, yes, this was supposed to be their first big single and they accordingly stuffed the first 20 seconds with histrionic, attention-seeking guitars and thunderous piano to make sure it hit its target. Or at least close to the target – it peaked at no. 10 in the UK singles chart.

Queen II is the exact intersection between two versions of the band. Their well-documented murky, metallic beginnings as quaint, bookish kooks, obsessed with fairytales and po-facedly dedicated to musical excess was just about to give way to the absolute pop perfection incarnation of Queen, leather trousers and Formby pastiches peeking over the horizon. With 'Seven Seas Of Rhye' in particular serving as the precise chronological point when things changed, the album becomes one of the most important in their whole career.

It was behemoth time. Queen's next single, 'Killer Queen', went even further than 'Seven Seas Of Rhye', ending up at no. 2 and landing them a slot on Top Of The Pops, and Sheer Heart Attack went Gold in the US. Elements of their more convolutedly whimsical past would be seen in later albums, but never with such candidness and success as on Queen II. Most importantly, for Mercury more than any of them, it meant no more support slots with Mott The Hoople. Stagecraft, wardrobe, light shows and medleys were now theirs to control from a position of power. And their omnipotence was most becoming.