Safeguarding concerns have been raised after a seven-year-old wandered out of Cheddington Combined School last month.
The incident took place on Monday, January 15, and is now being investigated by Buckinghamshire County Council.
A concerned mother of another pupil said: “I was shocked when I find out about it, that child was wandering around the village unsupervised and anything could have happened.
“I’m not happy with the arrangements at the school and I’ve complained to the headteacher in the past.”
A spokesperson for Buckinghamshire County Council said: “We are very sorry that a child got out of school grounds whilst in our care. The child went into an out-of-bounds area during playtime without permission from the staff on playground duty at the time. They were then able to open a bolt securing the gate, and leave the school premises.
“This gate has to be left unlocked during school hours as a fire escape, but there had been no previous incidence of a child opening it. The child went straight home and was returned to school by the parent within 15 minutes.
“An immediate review of the exit route took place, and an additional bolt was added at a higher level to the gate the same day. The school has since worked with the Board of Governors and the Bucks Education Safeguarding Advisory Service to confirm that their existing procedures keep the children as safe as possible, including the prevention of any further incidents such as this.
“The safety of all of the children at the school remains our highest priority, and with the support of their family the school is providing one-to-one sessions to help the child understand the importance of staying safely within school premises.”