One of my favorite vocals ever....Chrissie Hynde with the Pretenders, "Private Life"...
Apart from the fact that it's a stunning vocal by a ridiculously talented singer, what is it about the mix of this vocal that makes me like it so much? Is there a touch of phase or flange on it? 
 

Could have been a flanger or chorus used very subtly. More likely it was just double-tracked very tightly, with both tracks mixed at equal volume and possibly pitch-shifted a few cents apart. It takes a very precise singer to pull the trick off.

If that's a double tracked vocal then I am blown away. I can't detect any differences at all. 

Great vocal yes. Bass line is cool though. It might be too good for double tracking but maybe some very subtle modulated effect for sure.
 
Ben could well be right with the Leslie concept below. Feeding a vocal out to a Leslie and micing it and mixing it under the original vocal track is a nice idea. It can give that liquid movement effect to anything that it is applied to. You also get that very slight pitch shifting going on too as the horns come near and move away from you or the mic.
 
Choral seetings are usually a little faster than the effect on this track maybe (not sure) I modified my Leslie to run slower in chorale when I had one.  Fantastic for synth pads. I had two choral settings.

Leslie!!  There is Leslie all over this track.
 
Ben

Leslie speaker eh? Well that's interesting. I might give it a whirl, I think I have a Leslie simulation in Amplitube. 

Don't think its a leslie on the vocal.  Sounds more like slight flanging.  Don't think its a doubled vocal either.

I get flangers and phasers mixed up. I really need to sit down and listen to the difference between them sometime. I guess as a guitar player I never really used stomp boxes - if I had, doubtless my ears would be more attuned to the character of each. For instance, the backing vocals on Bryan Ferry's "Don't Stop The Dance." Am I right in thinking that's a phaser? 
 

A flanger or chorus would be the easiest way to get the effect. The primary difference between the two is the length of the delays: flangers using longer feedback delays than choruses. 
 
But yes, it really can be done with double-tracking. Listen to David Gilmour's vocals. They're nearly all double-tracked, as are his guitar solos. But he's so good at it you rarely notice that they're double-tracked.
 
The Bryan Ferry tune is definitely double-tracked, maybe even triple-tracked on the BGVs.

Yes, a phaser is a phaser set on stun? A flanger is a phaser set to kill... Van Halen got some interesting effects using both.