Jailed reporter's letter says hacking 'widely discussed' at NOTW

• Letter differs from version given by News Int to Commons
• NOTW lawyers claim James Murdoch evidence 'hard to credit'
• Law firm: evidence 'inaccurate, self-serving and misleading'
• James Murdoch and other NI execs may face Parliament again
• Tom Watson MP: 'one of the largest cover-ups in my lifetime'