The British Islamic State militant nicknamed 'Jihadi John' warned the taxi driver, from Greater Manchester, would be the next person to die after father-of-two Mr Haines was beheaded in a disturbing video.Mr Henning, nicknamed Gadget by colleagues who praised his sense of humour, was also an aid worker and is believed to have been working for a Muslim charity in a refugee camp.He had felt a 'pull' to return after a previous visit and was filmed packing an aid convoy containing nappies and tinned food in Salford before he left for his latest mission.The development came as David Cameron said today that people will be 'sickened' that the man who killed Mr Haines could be from Britain.The Prime Minister described Mr Haines as a ‘British hero’ - and warned: 'We will hunt down those responsible and bring them to justice no matter how long it takes.’ISIS were ‘not Muslims they are monsters’, he said, and added that UK could not afford to ignore the severe threat the jihadists' spread posed to both world and domestic security.(dailymail.co.uk)Bakudaily.Az