In 2008 Robert Henderson, then of the British Library, completed a PhD thesis at the University of London entitled "Vladimir Bursev and the Russian revolutionary emigration: surveillance of foreign political refugees in London, 1891-1905." Chapters 3 and 4 describe:
"...how, despite (or perhaps because of) its reputation as (in Trotsky’s words) a ‘sanctuary’ for political exiles, the British Museum gave readers’ tickets to plain clothes policemen from Scotland Yard to enable them to keep an eye on refugees working in the Reading Room. Following the Greenwich Observatory bomb outrage of 1894 (the inspiration for Conrad’s Secret Agent) it was found that information on the explosives had been taken from a book in the British Museum, and the Museum’s authorities agreed to remove a second edition of the book on explosives from the catalogue and keep it in a reserved collection. (Apparently the origins of the collection of books suppressed on security or legal grounds which was still in place when I worked at the Library, when copies of ’Spycatcher’ received under legal deposit were placed in a Deputy Keeper’s cupboard under lock and key). This eventually led to the arrest of the writer and journalist Vladimir Burtsev by one of the plain clothes policemen with a reader's ticket as he left the Museum Reading Room. Burtsev was subsequently the first Russian exile to be imprisoned in Britain. The case of Regina v. Bourtzeff remains central to law in this area and was recently cited, as Robert points out, in the litigation concerning the deportation of Abu Al Hamza" (Andrew Prescott, Dept. of Digital Humanities, Kings's College London, Humanist Discussion Group 12-03-2013). The links within the quote are my additions..