Bravo, Colin!!!
And now a question:
Is there some way of copying the properties of an existing material into a new material?
As displayed in your tutorial, it is often desireable to have a bump material which has almost identical properties to the colour material. Ctrl/drag a material to the Material folder doesn't work but would be useful. I currently save the material twice with different names and then import and change the colour properties of the first material.
What would also be useful would be if we could include the bump and colour properties properties within one material. Perhaps I should request this. Can you foresee any problems with this?