Cheers Rob, the Sigma isn't easy to get the WB in some scenes- it has a tendency to get confused with anything other than bright scenes.
Probably not accurate to describe it as such, but when you try to adjust post using any of the settings it can create a very set change to the image, usually throwing a very specific colour cast (ie shade, overcast, florescent etc settings).
The options are really more like effect filters this was using 'sunny' WB and gave a slightly warmer hue.