Liam Scott required almost 24-hours of hospital treatment following the shooting on Tuesday evening and underwent an hour-long operation on Wednesday afternoon to remove the pellet.

He had been happily playing football in the back garden of his home on Osborne Road at around 8.20pm, when he climbed a tree after hearing people laughing and playing.

Father Andrew Scott, who lives at their home with partner Alison and son Shane Green (12), said he was on the computer at the time when he suddenly heard Liam screaming.

Mr Scott, who saw his son’s arm covered in blood, said: “He was a little hysterical because he had never seen so much blood.”

Liam calmed down when paramedics arrived and he was taken to Queen Elizabeth Hospital, King’s Lynn. An X-ray found the pellet still lodged in his arm, so Liam had the operation at 4pm the next day and was in recovery just before 5pm.

In his warning to others on the dangers of air rifles, Mr Scott said it was only the matter of half an inch and the pellet would have gone through his arm.

He said: “Liam gets involved in all sorts of scrapes around the house, but you don’t expect to take him to the hospital after being shot.

“He hadn’t done anything wrong and it was painful to see it.

“It’s lucky it hit his arm and not his chest or face. It was in his own garden, so they’re not safe in their own gardens any more, it’s very annoying.

“I’m not saying you shouldn’t ever have them (air rifles and BB-guns), but as parents you let your kids out and you think they’re safe and this time he wasn’t.”

Liam, a keen footballer who currently plays for Wisbech St Mary Yellows and has just been accepted into the Peterborough United Soccer Skills Centre, was still feeling the psychological after effects on Thursday.

Mr Scott said Liam is always outside playing football, but since the incident he had struggled to get Liam into the garden for a kick about. He added: “He’s outside all the time playing football, but I can’t get him out there now. He loves a kick about, but at the moment he won’t do it.”

A spokesperson for Cambs Police confirmed officers are investigating the incident.