Jihadi who helped train 7/7 bomber free after five years

Exclusive: Release prompts claim Islamist was US informant while he was assisting leader of 2005 London attacks

• The 7/7 questions that remain unanswered
• Babar: 'I'm willing to kill American troops'
• 7/7 victim's father on Babar's release
• Court transcript: US v Mohammed Junaid Babar