Legal Deposit in the British Library
Introduction
Publishers and distributors in the United Kingdom and the Republic of Ireland have a legal obligation to send one copy of each of their publications to the Legal Deposit Office of the British Library within one month of publication.
The right of the British Library to receive one copy of every publication distributed in the United Kingdom or Republic of Ireland is based on the Legal Deposit Libraries Act 2003 and the Irish Copyright Act 1963 (currently being replaced by similar provisions in the Copyright and Related Rights Bill of 1999).
The principle that a national printed archive should be maintained by a legal requirement to deposit has been well established for almost four centuries and has great advantages for authors and publishers:
Publications deposited with the British Library are made available to users in its various reading rooms, are preserved for the benefit of future generations, and become part of the national heritage.
Publications are recorded in the British Library Public Catalogue (BLPC), which is accessible on the World Wide Web, and which will remain an essential research tool for generations to come.
Most of the books and new serial titles are listed in the British National Bibliography (BNB), which is used by librarians and the book trade for stock selection, is available in printed, CD-ROM and online formats, and has a world-wide distribution [...]
Categories Exempt from Legal Deposit Regulations
Publishers are not required to deposit the following categories of material unless a written demand for them is made by the British Library:
Internal reports
Examination papers
Local transport timetables
Appointment diaries; wall and desk calendars; posters
[...]
Other Legal Deposit Libraries
The deposit regulations of the Copyright Acts 1911 and 1963, with slightly different conditions, apply also to the other five legal deposit libraries:
the Bodleian Library, Oxford
the University Library, Cambridge
the National Library of Scotland
the Library of Trinity College, Dublin
the National Library of Wales
http://www.bl.uk/about/policies/legaldeposit.html