Three 13-year-olds - two boys and a girl - were expelled from the £30,000 a year Bedales school in Hampshire after they were involved in the theft of a bottle of whisky from a Waitrose store, and a subsequent sexual encounter in a sand pit.
The school is famed for its laid-back approach - there is no school uniform and children address staff by their first names.
Following the children's expulsions, the school's head wrote to parents of year nine pupils, saying:
'On the penultimate Wednesday of term, four Block Three students were involved in a series of disciplinary incidents, starting with one of them stealing a bottle of whisky from Waitrose and ending up on their return from Petersfield in the sand quarry.
'Following a formal investigation of these incidents and further questioning at the resulting disciplinary hearings, I asked three of these students – two boys and a girl – to leave the school. One boy went for theft, the other two for sexual misconduct.'
A spokesman for the school would not reveal whether or not the police were involved, but said the 'relevant authorities' were aware of the incident.