A copyright may represent a substantial asset for a person or company. The UK does not have a formal copyright registration process as in the U.S.A. — in the UK, creating the work creates the copyright.
The British National Bibliography (BNB) is the single most comprehensive listing of UK titles. UK and Irish publishers are obliged by law to send a copy of all new publications, including serial titles, to the Legal Deposit Office of the British Library; hence, the BNB is a list of copyright registrations. The British National Bibliography, was originally a weekly catalog which which became a reference for book selection, cataloging, and for retrieval.
A Free BNB Web service to be launched in January 2009 will make the BNB available through the British Library Integrated Catalogue web pages. At that time, the CD-ROM version of BNB will be withdrawn. The current consolidated catalogues available on the BL website certainly correspond to a large part to the BNB. The British Library Automated Information Service (BLAISE), allowed a BNB search back to 1950, but I do not know if those catalogue records were transferred to the current BL website’s Integrated Catalogue, but it appears that the the new Web service will include these records.