In April 1980, the US launched Operation Eagle Claw - a daring but ultimately disastrous attempt to free dozens of hostages held captive in the US Embassy in Tehran. The rescue mission ended in tragedy almost as soon as it began. Rob Walker spoke to Mike Vining, a member of the US special forces team in 2015. This programme is a rebroadcast (Photo:Special forces troops returning from the failed mission. Credit: US Army)