Thanks for the suggestions everyone. It's not a bad model, it just has hundreds of nodes because it's architectural and they're NURBS modelled as separate entities originally; not your average Poser prop.

I found the very simple solution was to apply the desired material to one node, then right-click in the materials window, select all, then right-click again and apply to all. Works a treat without having to remap the UVs (a relief because UVMapper won't go on Mac and I didn't want to bother hunting for a free alternative! Any Mac UVMapper suggestions welcome though. Aside from rebuilding it in Wine Bottler if possible).

Thanks for the suggestions again.