AFAICT someone might go to jail for owning a book (not sure if paper or electronic):
>From wikipedia (old revision): https://en.wikipedia.org/w/index.php?title=Abu_Hamza_al-Masri&oldid=609513570 --- Guilty of one charge of "possessing a document containing information likely to be useful to a person committing or preparing an act of terrorism"[31] under the Terrorism Act 2000, s58. This charge under the Terrorism Act of 2000 related to his possession of an Encyclopedia of Afghan Jihad, an Al Qaeda Handbook and other propaganda materials produced by Abu Hamza.[32] ---
