Pictures have emerged of a six-year-old in Britain being groomed for jihad. Brandishing a sword in front of the black flag of Islamic State, the boy raises his right index finger, a traditional sign used to signify that Allah is the one god. The photos were taken in a terraced house in Luton.

The boy is the son of Ibrahim Anderson, a British Muslim convert who was convicted this week of setting up a stall on Oxford Street, London, with the intention of recruiting for Islamic State.

Just as photos have emerged from Islamic State of young children being groomed for jihad, so too Ibrahim took pictures of his own children glorifying jihad. Another picture, snapped on his mobile phone (and obtained by the Mail on Sunday), shows the boy’s eight year old older brother in a similar pose wielding a sword in front of the flag – while sporting a Kermit the Frog t-shirt.

In another, the boys’ toddler sister is sat smiling in front of the flag. She’s wearing leggings, a flowery long sleeved top – and a pink hijab despite her young age.

Last year pictures and videos emerged from Islamic State in Syria showing children as young as three being taught how to fight jihad in Islamic schools in the region using real guns. In one, a narrator explains: “The teacher, Abdullah, spends a few minutes explaining the theory of jihad, or holy war. Then he moves on to its practice.”

Anderson was convicted at the Old Bailey on Friday for “inviting support for Islamic State” in the first successful prosecution of its kind, along with Shah Jahan Khan. The two set up a stall on Oxford Street, a busy shopping venue in central London, where they handed out leaflets promoting Islamic State.

The two belong to the same group of extremists who launched Muslim patrols in central London, abusing people on the streets who didn’t conform to their Islamic values. Michael Adebolajo and Michael Adebowale, who killed drummer Lee Rigby outside his barracks in Woolwich, South-East London, and Siddharta Dhar, the new IS executioner replacing Jihadi John, were also part of the group.

Anderson and Khan were brought to justice after a fellow Muslim reported them to the police three times.

Other photos found on Anderson’s mobile phone show four other children, thought to be members of his family, in front of a banner reading ‘Khilafah est 2014’; a reference to the Islamic State caliphate set up that year.

Anderson’s stepfather, Martin Warner, told the Mail: ‘I can’t believe he made his children pose with the IS flag – it is disgusting. He is a total idiot, a fanatic. He is the sort of person who would blow himself up or plant a bomb. He is dangerous. They should throw him in prison and throw away the key.”

Conservative MP Philip Hollobone said: “Not only is this child grooming, this is child abuse. We can’t have children being brought up in this country to become potential suicide bombers, groomed by their own parents. These children should be taken into care, if appropriate.”