Fred McC - I had a similar experience in Liverpool many years ago - perhaps mid-70s. The Reference Department card-catalogue showed four volumes of Bronson - only two could be found. Similar gaps were found when I looked for other folk-song collections. The librarian I spoke to had no explanation other than theft - unimaginable to me at the time, but far more expensive volumes have been systematically looted from British libraries, both from public collections and from University libraries where you might expect a higher level of security. But it is also deplorable that reference books such as this have been arbitrarily discarded for space-saving reasons in the way you describe. Equally criminal.

Ross