Thanks again Guys.
I applied a texture to the back of a face in the component where it is never seen, saved the component with the rest of the faces using the default material and now when I import it the material comes with it. If I now change the colour using Component options it works (although the hidden face always stays as the texture I applied directly to it).
However I am still confused, because when I import the component it comes in showing the default material until I drop it in the model when it changes to the texture specified in the component options.
With the original models I did (second sample above) they come in showing the texture specified correctly and they work perfectly when using the component options - AND - there are no hidden textures in them.
Also - with the original models, if I change the colour in component options then re-save the component, when I then import that into a new model it comes in the correct colour and brings that texture with it (the original texture is gone, as expected) - but I did not place any hidden textures in the component before saving it.
Very strange - but at least for the time being I have a solution (until I can work out what I may have done differently the in the original models).