I can’t tell you what is wrong with your model. It is a very strange. But I was able to make the flickering go away by adding a couple more vertice loops in the area that was flickering. I guess there wasn’t enough polygons for blender to correctly render the smooth shading.
Sketchy: I added a couple of loops towards the bottom of the knobbly bit as you suggested and it fixed the problem.
The only odd thing in that area is that the faces that connect the head to the knobbly bit are set to solid and the rest of the faces on the head are set to smooth, the idea was so that head would have a flat bit at the top around the knobbly bit.
Maybe the fact that it goes from Smooth to Solid to Smooth somehow mucks things up.
Anyway, I am glad its fixed and I can keep plodding on!