The guardian of a vulnerable 13-year-old autistic boy is outraged by “inadequate punishment” at Sandwich Technology School after he was tied to a post by fellow pupils.

The woman claims the school called her the next day reporting that her nephew, who cannot be named, was bound by two boys while he waited for a school bus at the end of lessons on Tuesday, March 22.

But after complaining to Dominica Parker, manager of the school’s Endeavour College, the woman, who lives in Staple, says the only discipline the alleged culprits received was exclusion from their lessons for the day. She has reported the incident to the police.

A statement by head teacher Tracey Savage said: “It would not be appropriate for me to comment on an individual student.

“I can say that any breach of discipline is dealt with in accordance with our published student behaviour management policy and, where appropriate, clearly defined sanctions are imposed.”

“If he had missed the bus he probably would have been scared to tell me, in case he got into trouble. He is very, very vulnerable.”

The child moved in with his aunt when he was 10. She treats him as her own and he likes to call her mum.

He is also diagnosed with Attention Deficit Hyperactivity Disorder and Obsessive Defiance Disorder. His aunt describes him as a “hyperactive and bubbly, but very nervous boy” whose needs are very complicated.

He copes with his conditions by following a rigid routine, and struggles when the regime is interrupted, when meeting new people or when he is in crowds.

He accepted his place at Sandwich Tech after being told it was a non-contact school.

He has not been given a place at a specialist school because he thrives academically, and his main struggle is with social interaction.

The woman claims he became even more withdrawn after the incident and did not tell her about it.

She thought his change in behaviour was due to tiredness. The school told her what had happened the next day and he later told her the boys intended for him to miss his bus.

She said: “If he had missed the bus he probably would have been scared to tell me, in case he got into trouble.

“He is very, very vulnerable.”

A teacher released him in time to catch the bus.

The aunt, who has a son with severe autism, said she was disappointed with how the school had dealt with the matter.

She said: “All they have done is taken the boys out of class for a day. They think that’s adequate.

“The school didn’t tell me themselves what the repercussions would be. He had to come home and tell me.”

When told of the school’s statement, the aunt became teary. She said: “They have failed to protect my son and that’s all they can say for themselves.”

A police spokesman said: “Kent Police received this report at 9.56am on Tuesday, March 29. We will make further contact with the caller to obtain further details.”