What do you do after you have achieved everything there is to achieve in heavy metal? Do you, like Metallica, stay on perpetual tour and avoid the responsibility of ever having to produce new material. Do you, like AC/DC, produce albums by the numbers as a prelude to another monster world tour?
Or do you, as Iron Maiden have done at the tail end of a glorious career, produce your longest, most ambitious and musically complex album yet?
Metalheads disagree on many things, but they all agree on one thing – no band personifies the genre more in all its absurdities and glories than Iron Maiden.
The band’s cartoonish image obscures the fact that these are deeply serious players with the compositional skills of classical musicians. The best Iron Maiden songs are long, but they are never dull. The band understand too much about melody, tempo and musical tension to be boring.
Few bands would have the ambition, in an age of rapidly declining attention spans, to produce a double album 92 minutes and 11 seconds long. Fewer still would have the ability to do it.
Iron Maiden have pulled it off. The Book of Souls is (ahem) book-ended by two Bruce Dickinson compositions – If Eternity Should Fail and Empire of the Clouds, the latter clocking in at 18 minutes and one second (and you thought Rhyme of the Ancient Mariner was long).
Empire of the Clouds begins with a sole piano line as Dickinson slowly unfurls the story of the R101 airship – "for all your unbelievers, the Titanic fits inside" – which crashed on its maiden voyage to France in 1930. The band take hold of the melody and bring it on a musical journey which mirrors that of the ill-fated airship.
The Red and the Black starts with a series of classical guitar arpeggios, followed by something of a Celtic jig and then a "woah, woah, woah" chorus similar to that of Brave New World and so it goes on twisting and turning for another 13 minutes without ever flagging.
For those who like old-school Maiden (pre the 1999 reunion) the lead single Speed of Light is a relatively short (five minutes) return to up-tempo glories.
Not all the songs on the album are great. The Great Unknown and The Man of Sorrows do not quite match up to the rest of the album, but when The Book of Souls is good it is bloody brilliant. If you like Iron Maiden, you will love this album.