Quo didn't always play their trademark battered Telecasters [Rossi has often moaned that the typical Quo sound has less to do with the Telecasters and more how he and Rick play(ed)] and Nuff had a liking for less than long scale basses (his legendary Fender Mustang and the later Travis Beans/Kramers, which were medium scale) so the Gibbie might have fitted right in. But I don't rule out that they were "TV studio loaned" either. That happened quite often in the 70ies.