article_snippet: GCHQ Headquarters, based in Cheltenham, is the Government's main listening post and is allowed to monitor people's 'communications' to uncover terror threats .
article_snippet: That compares to 1,291 approvals for GCHQ and 652 for MI6.
article_snippet: MI5, which makes the vast bulk of such applications, was given 48,639 authorisations last year.
highlights_snippet: Agents at GCHQ monitor 'large numbers of items' to uncover terror threats .
  
highlights_snippet: Spies use 'bulk interception' powers to track down terrorists such as ISIS .
  
highlights_snippet: Spies at GCHQ, MI5 and MI6 have been  sacked for 'inappropriate' snooping .
  
highlights_snippet: Spies have been sacked for misusing a vast computer system containing millions of pieces of personal data about British citizens.
highlights_snippet: Intelligence and Security Committee found that MI5, GCHQ and MI6 had all disciplined – and in some cases sacked – operatives for unapproved access.