I have absolutely no idea what’s causing this problem. Whilst improving the blade on my sword I removed a few vertices which were messing up the reflections. This created a few holes which I then filled in with new faces. However these new faces don’t appear on the rendered image and I can’t figure out why.
The holes are definately not there in the model. Anyone know why this happens?
Here are 2 images of the model in Blender and the render.
Mmmm, play with H Key to be sure of what you are looking at,
Usually I would have told you to recalculate the normals. but this does not seem a normals issue.
Be sure that the faces are really there 
Stefano
After a closer look the faces are actually there, but for some reason the blade texture isn’t being applied to them :-?
Aha! did you use UVmap?
Stefano
No it’s just an env map with chrome look material (I used the settings from the tutorial on this site). I thought it might be a problem with the material/texture so I tried using another, same result:
It seems Blender hasn’t updated the new faces with the texture.
Are you sure they’re assigned to the correct material group? (same as the blade)
Problem solved, it was caused by that part of the blade being smoothed whilst those new faces were not. I guessed it would be something simple like that 
Thanks for the replies anyway