Alan Henning
David Henning's family have asked that this picture is used instead of a still from the Isis video released last night. Henning family

The British man threatened with execution at the end of the David Haines execution video video has been named as aid worker Alan Henning.

Henning, 47, is believed to have been working for a Muslim charity in Syria when he was kidnapped at around Christmas time last year, by Isis (Islamic State) militants.

The former taxi driver from the Manchester area was seized while travelling with a humanitarian aid convoy, shortly after crossing from Turkey into Syria.

In the Islamic State video showing the execution of fellow Briton and aid worker David Haines released late on Saturday, Henning is shown with shaved head, wearing an orange prisoner's jumpsuit.

In a voiceover, 'Jihadi John' threatens Henning with execution unless Britain withdraws its support for forces battling Islamic State.

A Twitter user said he recognized Henning immediately after the video was released.

"HOLY S--- I KNOW THIS MAN," said a tweet from @SaiyanSyrian. "The man ISIS are threatening to behead is an aid worker who went with a British humanitarian convoy to help Syrians."

Henning was believed to have been travelling to Idlib in Northern Syria when he was abducted by Islamic State militants.

Journalist Tam Hussein, who investigated Henning's disappearance for NBC News, told the New York Daily News that Henning had been advised not to travel to Syria.

"Henning was told not (to go into) Syria… but insisted on going in b/c he had put in so much time and effort in the project," wrote Hussein, who said he investigated Henning's disappearance for NBC News earlier this year. "Henning wanted to make sure aid reached the intended. Henning was genuinely trying to help the Syrian refugee crisis — nothing more. People spoke very highly of him."

Henning is believed to have been held in an Islamic State-controlled jail in Al-Dana, before being moved to Raqqa, Islamic State's power base in Syria.

Henning's last contact

Journalist Harald Doonbas told Buzzfeed that he interviewed a Syrian activist who claimed to have been held in the same cell as Henning.

He said that Henning was in good spirits, as he believed that because he was an aid worker he would soon be released. He told the man that he was from the Manchester area and was working for an Islamic NGO.

Islamic State has previously released videos of the executions of US journalists James Foley and Steven Sotloff. The videos contain warning for the US and UK to cease air strikes against Islamic State, and to stop arming Kurdish forces battling the militant group in Iraq.

At the end of each video, the next man to be killed has been shown kneeling with shaved head.

The British media initially did not disclose Henning's identity, which was reported by news organisations in other countries, before it was revealed by the BBC this afternoon.