He spent his mornings, afternoons and evenings sending thousands of tweets of propaganda about the Islamic State militant group, acting as the leading conduit of information between jihadis, supporters, and recruits.

His tweets, written under the name Shami Witness, were seen two million times each month, making him perhaps the most influential Islamic State Twitter account, with over 17,700 followers.

Two thirds of all foreign fighters on Twitter followed him. When a fighter's Twitter account is suspended, he often promoted the new one and urged people to follow it.

He spoke to British jihadis regularly, before they leave to join the Islamic State, after they arrived, and if they died he praised them as martyrs.

He has until now been able to remain anonymous, avoiding questions about his motives and his central role in the Islamic State's propaganda war, but a Channel 4 News investigation can today reveal that the man operating the account is called Mehdi and he is an executive in Bangalore working for an Indian conglomerate.

Channel 4 News has chosen not to reveal his full name as he says his life would be in danger if his true identity was made public.

Mehdi said he would have gone to join Islamic State himself, but his family were financially dependent on him: "If I had a chance to leave everything and join them I might have.. my family needs me here."

On his Facebook pages he regularly shares jokes, funny images and talks about superhero movies, posting pictures of pizza dinners with friends, and Hawaiian parties at work.

Elsewhere on Facebook there are indications of his Islamist ideology, in conversations about Libya and Egyptian uprisings.

After being contacted by Channel 4 News, Mehdi shut down the Shami Witness account.

(4 news)