Model has strange shade points I did a bit of re-topo and suddenly when I smooth the model it creates this weird effect seen below:
 



I've 'Removed Doubles' and made it 'Double Sided'. (I've also selected 'Auto 
Smooth' which has helped a little but I still get these weird cut off points.

You can see it near the top right section of the eye:


Would love to know the solution to this problem as it really messes with the render.

Here's the .blend file: http://www.pasteall.org/blend/34280
It's simply that some of your normals that are wrong... 

Select all faces CtrlA, press CtrlN to recalculate the normals (or from the 3d view header use Mesh > Normals > Recalculate Outside).

This can happen when creating faces and selecting vertices in a different order than blender expects.