Aah - now I get it!

 What puzzled me is that there are 25 objects in the scene, with 25 mats in the Blend file - obviously one per object - but 43 textures, with names that don't clearly identify with the object - such as bump1.  Taking a closer look at the Blend, I see, when selecting one of the objects, a name for both the mat and texture.  What I couldn't figure out is how to associate a mat with it's accompanying texture.  What I eventually worked out was you simply append the mat file and the texture also loads.  Pic a different texture and you can mix and make different mats.  Very flexible with endless variations.

Got so used to expecting very complex actions in Blender, I couldn't see the wood for the trees :)

Thank you for putting me right :)