'David Cameron, I hold you entirely responsible for my execution': British hostage forced to condemn UK government before beheading by Jihadi John who threatens to kill another Briton next Father-of-two from Perth, Scotland, abducted by militants in Syria last year He was shown on knees in jihadi video of US journalist being beheaded In the footage, the extremists also threaten to execute another Briton Militants previously beheaded journalists Steven Sotloff and James Foley By STEPH COCKROFT 13 September 2014 The Islamic State has released a video claiming to show the beheading of British captive David Haines. The father-of-two, an aid...