could someone tell me what is causing this? I thought it might be transparency but that is 0 so i dont know how to stop the red glow of light shining threw this guys head? 

Are you using SSS?  If so, your settings are too high.  Screencap the skin Material Shaders.

"blank look" sorry no clue what sss is. how do i screen cap? 

SubSurface Scatter.  I would need an image of the material room to assess what is actually going on.

this is the skin of the face. m4 

I agree with hborre. It's likely an issue with the subsurface scattering but we would need to see the edit tab in the material room.

thanks. from your comments the penny dropped and i worked out the situation. I had turned off the raytrace because the girl's hair with it on takes forever to render. but with it off you het this lightbulb in the head effect in the m4 model, 

What are you using to render? Firefly or Superfly? 

Decrease the Scale value on the Scatter Node.  Bring that value down to 0.1 and rerender your scene.  If the glow has decreased but is still prominent, reduce it to 0.01.  

This channel may be the source of your problem.  To be frank, the skin texture requires a thorough revamp for Superfly rendering.  But, considering that you are creating scenes for a comic format, it is better to tweak the existing settings to make the render presentable.  

Let me point out that the street lamp illumination is too bright.  If it is an actual light prop, I advise changing its attenuation to Inverse Square; it will give you a decent light falloff with distance.  To fill in the shadows, add a low-intensity light with no shadows towards the lower right-side of the scene. 

You can turn off the raytracing for just the hair in the properties panel so you don't have to have it off for everything.

cheers guys you are awesome. I admit I should have learnt this stuff years ago but lighting has always bugged me. (only trouble is now im older i forget stuff easy and have to make notes on everything. thanks a lot for the help, this is an easy scene so im going to make the changes and recut the full scene. 

I ended up changing the scatter node value to 1 because the other ones i tried made his head look like rubber (and his names not ken!)  I changed the lighting and now happy with the results. thanks for the help.