2008 has seen more soul divas than you can shake a beehive at and although the increasingly self-destructive Amy Winehouse frequently gets the credit for this sudden renaissance, her contemporaries are actually a lot more singular than mere bandwagon jumpers.
Duffy, in particular, stands out. Her voice is no stronger than Adele's and she lacks the charisma and wit of Estelle but, simply put, her songs are better. 'Warwick Avenue' was a magnificent piece of '60s inspired pop with a timeless melody, while 'Mercy' was motor city glam transplanted to Bangor - and all the greater for it.
No matter how good your album is (and Rockferry is undoubtedly a fine record) there is bound to be a falling off in quality by the time you get to the fourth single release. Yet, while 'Stepping Stone' doesn't quite have the majesty of 'Warwick Avenue', the oomph of 'Mercy' or the epic sweep of the song 'Rockferry', the mood and melody is still strong enough and her voice sufficiently yearning to make it work.
Built round a finger-clicking beat that's pure Bacharach, Duffy relates a classic female empowerment lyric culminating in her stating she will never become the titular crossing boulder for the no-good cad the song is addressed to.
However, there is a vulnerability in her delivery, intriguingly at odds with the defiance of the lyrics, and it is this ambiguity that elevates 'Stepping Stone' from just another ballsy girl-power ballad into a thoughtful and emotional piece of music.