The child who appears in the so-called Islamic State's latest propaganda video shows the group is becoming increasingly desperate, experts have said.
The group's latest execution video shows the boy at the end, reported to be between four and seven, threatening that IS, also known as Isil or Isis, will "kill the kuffar", which means non-believers.
In the same video, another masked man, speaking with a British accent, calls David Cameron an "imbecile" and mocks the RAF's bombing campaign against IS which was recently extended to Syria.
Five men accused of spying for the British security services, dressed in the orange jumpsuits reminiscent of earlier IS victims, are made to kneel and then shot in the back of the head.
The little boy appears at the end of the 10-minute video after the executions. Dressed in military fatigues and wearing a black headband, he gives his warning in broken English. Newspapers speculated that the boy could be the son of a woman who fled London for Syria, Grace "Khadijah" Dare. She left for Syria in 2012 and is believed to have married a jihadi there.
The press was also quick to dub the man the new "Jihadi John", the successor to Mohammed Emwazi, the Briton who carried out executions in previous IS propaganda videos and is believed to have been killed in a drone strike in November. The Sun referred to the boy as "Jihadi Junior".
But experts said the appalling video was intended to deflect attention from its recent setbacks.
In recent weeks, IS has suffered defeat on the battlefield, most recently in Ramadi in Iraq.
Lord West, former First Sea Lord, told The Sun: "Terror is part of their policy because they think it shakes and rattles the West. But it’s a sign of desperation, not strength. We need to steadily keep applying pressure."
Security expert Shashank Joshi told The Press Association the video was aimed at "threatening, goading and provoking" IS's opponents in the West.
"I think there is an overall sense in which they have had relatively few successes in the past few weeks," he said.
"They have been pushed back and these videos are a method to try and maintain support."
Charlie Winter, a specialist in IS propaganda, told The Times that the video was "unremarkable" except for the child and the nationality of the executioner.
Richard Kemp, a former colonel who commanded British forces in Afghanistan, told the Daily Mirror: "No doubt there will be subsequent appeal to British Muslims to attack other British people. The inclusion of a child is designed to shock us as it has done in previous videos of children holding heads up and things like that.
"This gunman is trying to look tough. But he conceals his face and is obviously scared of being killed by our forces. This is exactly the kind of cowardice we have come to expect from people like him."
The Guardian reported that the five men executed were Ha'il Marwan Abdul Razaq, 40, Ubi Muhammad Abdul Ghani, 26, Faisal Hamud al-Ja'far, 25, Umaar Hamud al-Ja'far, 30, all from Syria, and Mahyar Mahmud al-Uthmaan, 31, whose nationality is unclear.
The security services are understood to be examining the footage.
A Foreign Office spokesman said: "We are aware of the video and are examining its content."