The perennial problem for teen-idol bands of either gender is growing up: after just a few years of pubescent adulation, it's inevitable that both the fans and the bands themselves will start to chafe against the confines of the simple pop verities that have sustained both thus far.
But how best to effect the change to a more mature sound? Usually, it's done with a salvo of solo albums through which the individual singers hope to establish themselves as R&B stars. So it's kudos of sorts to One Direction for going in the opposite direction and pushing their singalong pop into more of a rock orientation.
The last album, Midnight Memories, saw the successful infiltration of power-chord guitars into their sound, along with the thoughtful touches furnished by Ed Sheeran's songwriting. Now, with Four, they've all but gone the full New Joisey route, with several songs making brazen grabs for that rock heartland territory.
It's clear right from the opening piano ostinatos of “Steal My Girl”, which are but a screen-door-slam away from classic Springsteen territory; and later, the big drum groove and reedy riff (that could be organ or accordion) transform “Girl Almighty” into something akin to one of the Boss's recent Americana/cajun knees-ups.
It's certainly a long, long way from the standard X Factor fare with which their career began, and when you factor in the fizzing fuzz-guitar riff and American inflections of Harry Styles' bombastic rocker “Where Do Broken Hearts Go”, the big-hair shadow of New Jersey's other favourite sons Bon Jovi looms large over proceedings.
Elsewhere, another emblematic keyboard motif brings Bruce's tectonic emotional power to “Night Changes”, with its striking street-operatic image of how “her mother doesn't like that kind of dress, it reminds her of the innocence lost”, a piquant contrast to the innocent affection of Sheeran's “18”, with its reference to the playground underscored by his characteristic melodic resolution.
Less agreeably, there's something of Coldplay's vaunting nebulosity about closer “Clouds”, while the reverberant guitar riff of “Ready To Run” might have been emailed in from The Edge, so eagerly does it yearn for a stadium to echo around.
It's not all suddenly-grown-up rock music, of course, with tracks like “No Control” and “Fool's Gold” retaining the boys' perky teen-pop charm; and whatever style is adopted, the choruses are all reassuringly collective singalongs.
But credit where it's due, particularly to Louis Tomlinson and Liam Payne, whose songwriting contributions dominate the album, pushing it firmly in the right direction.