New: Video purportedly shows ISIS murder of British Hostage

  • Alan Henning, British aid worker being held hostage by ISIS militants, reportedly beheaded in newly released video.
  • Henning, aged 47, was kidnapped in December 2013. 
  • Aid worker's wife Barbara had urged ISIS to release her husband in media appearances earlier this week.
  • UK PM Cameron said apparent murder showed there was 'no limits to the depravity' of ISIS militants.