Pomposity, insanity, galloping blasphemy: 1988’s Seventh Son Of A Seventh Son is a mighty Genghian cleave of a record, a progressive concept album that contains all that is glorious – and mildly deranged – about Iron Maiden. Strangely delicate melody juxtaposed with gazumping rhythmic pulse; wild theatrical delivery; dramatic, occult-referencing ideas. But while seen by some as the most fulsome of their career, it is by no means their easiest – indeed it took my (much) younger self years to fully appreciate its myriad subtleties over the more immediate ampage of Number Of The Beast or Powerslave.

Cranially speaking, Iron Maiden have always existed in a permanent youth dreamscape. It’s a beguiling and comforting place, a fusty land inhabited more by ‘swag’ – curled posters, lurid t-shirts, box sets and VHS tapes ("got, got, need") – than sound; real appreciation of the actual music came later. I got Killers, on cassette, first. From Andy’s Records at Cambridge market, aged nine, and chosen for the not insensible reason that ‘the monster’ (for a year or so Eddie was just ‘the monster’) was ‘biggest’ on that one. ‘Murders In The Rue Morgue’ and ‘Wrathchild’ were enjoyed enough to delve further, and Maiden eventually became one of the few steadfast musical constants through late childhood, early adolescence and beyond. They scissor-kicked over Carter USM and PWEI; muscled in on Helmet and Tool; galloped over Ed Rush and Optical and Ram Trilogy; they mounted the monitor behind Regis and Luke Slater and let off flash bombs over the heads of The Fall and Can. Maiden were the omnipresent entity; a simple but perfectly rendered rib-eye on an aural menu dominated by increasingly elaborate fusion, the dun-chucka-dun-chucka-dun-chucka of Harris’ bass a clarion call back home.

Musically, however, they were anything but simple. Sneak past Eddie, the flames and a merchandise net that would make Gene Simmons and Paul Stanley exchange furtive glances and take fevered notes, and you're left with a serious body of idiosyncratic work that has often been overlooked in place of the established ‘classic’ rock canon. A Maiden show still feels like a familial cult curiosity, albeit on a vast scale.

From a lyrical perspective much of Maiden's content stems from a well-read curiosity on behalf of Harris and Dickinson. It's best described as a combination of bombastic dramatic licence with historical fact, and total flight of imaginative fancy. Steve Harris just finished reading about the Battle Of Britain? Out comes ‘Aces High’. Dickinson up to the gills in Egyptology and Crowley? Have ‘Revelations’ and Powerslave... It’s an endearing trait, and it appeals to the inner hobbyist – history and literature are never far behind with Maiden, their lyrical world providing ample opportunity to research further, if you please. A heavy metal reading list, essentially. Personal angst and morose introspection, while by no means absent from the Maiden canon (see the Fear Of The Dark LP, for example), are not central.

Instead we have a thematic pleasure dome, a Xanadu of Harris and Dickinson’s buzzing frontal lobes. To the right, an expanse of swarthy scrub, rowdy mead halls and desolate steppe inhabited by warlords, demons, desperate troops and dashing swashbucklers, by soothsayers, nomads and wicked women. To the left, an oak-bound library with Tennyson, Crowley, Coleridge and Churchill sitting by the fire swilling brandy and discussing, oh, I don’t know – iambic meter, mountaineering and military disaster. It’s utterly preposterous. It’s totally fucking glorious.

On a purely narrative level, Seventh Son traverses both sides of the dome. An epic fantasy of Greco-Roman proportions shot through with literary references, the LP tells the story of a clairvoyant, who can foresee, but not change, his own demise. A moonchild, a seventh son of a seventh son, this character is the subject of intense interest by forces of both good and evil and struggles with both throughout. Lyrically, Steve Harris was reportedly inspired by Seventh Son, a novel by Orson Scott Card that told the story of soothsayers in the frontier West, while Dickinson drew on Alistair Crowley’s 1917 novel Moonchild.

Musically, the record was not a sweeping departure from the established template – but it certainly twisted the format enough to creatively revitalise a tired band. And, by all accounts the mid 80s were an exhausting time to be in Iron Maiden. The triple turbine of Number Of The Beast, Piece Of Mind and Powerslave - released in rapid fire succession in 1982/3/4, and backed up by mammoth world tours, had left the band creatively jaded. In particular, the extreme rigours of the 1984/5 World Slavery tour had rendered them physically spent. A legendarily gruelling trek in support of Powerslave, World Slavery took in 190 concerts over 331 days, double backing across the globe at the behest of notoriously tight-fisted manager Rod Smallwood. As stated by Steve Harris in the documentary Iron Maiden: Flight 666: "We just toured; album, tour, album, tour, writing, recording, touring. You were lucky to get a week off a year, and then it was (affects Smallwood’s broad Yorkshire accent) 'You’re bloody going back in the studio again...'"

Dickinson wanted to branch out musically on 1986’s Somewhere In Time – multiple acoustic numbers were mentioned – but his ideas were rejected and the resulting LP, although solid enough, was not a classic, and was a noticeably calmer affair than anything previously offered. However, it did usher in new ideas – particularly the use of synthesisers.

Seventh Son was to take it further. Rapid tempo changes, acoustic passages, the wide scale use of synths, strong narrative progression. It was hammy and bombastic, but it also contained a strange alchemical element – melody lines tower on top of each other and there is an atypical looseness to the playing that lends a feeling of controlled chaos. The actual heaviness of the record – as ever – is largely driven by the rhythm section and Dickinson’s inimitable vocal delivery. Maiden are something of an anomaly in the metal world; their guitar work is often surprisingly delicate. The playing of Adrian Smith, in particular, is gossamer light throughout the LP.

Structurally, the album can be divided into leather-bound epics and concise belters. ‘Moonchild’ is one of the latter, a period piece, the only truly 80s-sounding song on the album. In fact, the intro synth passages sound uncannily like the incidental music from Beverley Hills Cop 2 (think Ronny Cox jogging in the oilfields) but when it kicks in is one of the greatest moments in metal – Dickinson taking the role of Lucifer himself with his trademark, "Can you hear it up in the gods?" chutzpah: "I am he, the bornless one; the fallen angel watching you; Babylon, the scarlet whore; I’ll infiltrate your gratitude..."

‘Moonchild’ – probably the least obviously hook-driven of the many songs Dickinson and Adrian Smith have written together – contrasts strongly with ‘Can I Play With Madness’, three minutes of shiny radio friendly rock (to this day, it’s the only Maiden track you’ll regularly hear on the FM dial). ‘The Evil That Men Do’ is a great live track, certainly one of the steeliest encapsulations of Maiden in full live cavalry gallop, seemingly teetering on the edge of destruction while the title track offers a meaty and substantive centrepiece, a brutal progressive epic, almost the equal of Powerslave's ‘Rhyme Of The Ancient Mariner’.

Most dramatic is ‘The Clairvoyant’, a live favourite that will forever lend itself to a mental image of half of Argentina leaping up and down in some Buenos Aires soccer stadium, eyes trained in fervent rapture, arms stretched en masse toward Bruce Dickinson, the pied pilot of jousting...

Interestingly though, Harris has stated in interviews that songs from Seventh Son have not always translated to the live arena, particularly in the USA, where the album failed to go platinum. Perhaps this is because, in essence, Seventh Son Of A Seventh Son is a progressive metal record, and one which makes perfect sense when taken in the context of what Maiden have done since 2000. Leaving aside the stripped-back rawk of 1990’s No Prayer For The Dying and the noticeably darker records that continued into that decade (Fear Of The Dark, and the criminally underrated Blaze Bayley LPs X Factor and Virtual XI). Seventh Son feels like the logical linking point between the Maiden of 1988 and now.

Indeed, any talk of ‘classic era’ Maiden automatically ending at Seventh Son is disingenuous. The true ‘golden age’ of Maiden is post-2000 – the superlative quadrant of records released since then has completely nailed the combination of naked aggression and vast expansive bombast to greater effect than ever before. They have proved, with some style, that they’re far from a nostalgia act. See them on any new LP tour and you’re going to get all of, or most of, that record – and a good thing too. 2006’s A Matter Of Life And Death and 2011’s The Final Frontier are the best records that Maiden have ever made – more tumultuous, dynamic and downright bonkers than anything that has come before.

That said, Seventh Son Of A Seventh Son will no doubt continue to intrigue. It’s a wonderful album: a snapshot of a band gloriously out of step with the world around them, a truly eccentric odyssey that will ensure that wherever it may be played in the world, there will be always be some far flung corner forever Maiden, England.