There's an invisible line that none of us can see but most of us know is there. On one side sit integrity, originality, artistry and other nauseating words that end in "ty"; on the other, mawkish balladry, predictable chord progressions, lowest common denominator lyrics, gumboils and arthritis. Musicians certainly know about it, and crossing it often means platinum album sales and untold riches. But at what price? Your stock may rise with the record company and a headline slot at V Festival is all but inevitable, but such Faustian pacts don't go down well with critics and those who probably take their music more seriously than they should. Chris Martin has the Learjet, the Hollywood wife and the guest appearance on The Simpsons to crow about, but is he really happy? Snow Patrol too used to be a likable little band with spiky little indie songs playing gungeholes and Barflys before they got tired of driving up and down the M5 in a white, Bedford van. "I'm sick of struggling," Gary Lightbody complained to Satan. "Slow everything down," advised Satan. "Think simple. Think viral. Think Lion Woman from X Factor warbling all over it at Christmas. Off you go Lightbody."

Then there are bands that go awry for inexplicable reasons. They just lose the plot, go soft in the head, believe their own hype. Unspeakable wealth and fame don't seem applicable somehow, and yet, for whatever reason they circumnavigate taste entirely, crashing through the invisible line and winding up with a product that feels wrong on almost every level. Regrettably, Shearwater seem to have forsaken the gorgeous subtlety that made them such a hidden treasure not so long ago to produce this Frankenstein's monster of an album. It now seems a very long time since their double-disc opus Palo Santo, made in 2006, that while undoubtedly driven by emotion, also drew on the genius of bands like Talk Talk to somehow keep everything in check. That emotional edge now seems like the thin end of the wedge, and The Golden Archipelago is a folk album so overwrought and worthy that it sounds like one of Christy Moore's hangovers.

The 72-page booklet that accompanies, full of sepia-tinted pictures of mountains and black and white shots of slaves, screams "epic!" before the laser even hits the CD. It's as though they set out with the intention of making the most heroic and legendary record possible, and have somehow got lost in a solipsistic bubble of self-belief. The Golden Archipelago is how Elbow might sound if Guy Garvey were the guy in the Book of Job. It gushes with sentimentality and revels in its own bombast.

One can almost see them locked away in a studio deliberately denying themselves contact with the real world as they get drunker and drunker on their own success. Having emerged back to normality, what they deliver is a stinker that makes you think of post-Fish Marillion no matter how hard you try not to, exemplified best on 'Corridors', a song that does for progressive rock what Toby Young does for fashion.

From the outset on ‘Meridian’, a song that sounds like Alan Partridge's vision of Ireland, to ‘Missing Islands’ at the end with its stings and creeping piano, it's as though they intend to wring out every ounce of emotion they can, and it's exhausting for the listener, like being at a funeral that, unlike the chap in the coffin, refuses to die. We also get Clannad on 'God Made Me', latter-career Pink Floyd on 'Runners of the Sun', while tracks like 'Castaway' and 'An Insular Life' would be perfect soundtracks to a rugby World Cup for ITV.

Only there's no Rugby World Cup this year. Thank Christ.