Parents are asked to pay£17 for each examination - with a maximum of nine subjects -at Wildern School in Hedge End near Southampton. But the scheme has been questioned by teachers' unions and parents at the school, which has a 100% pass rate in getting GCSE A to G grades for all pupils entered.
The headmaster, Jeffrey Threlfall, said that in the past he had never had to cash the cheques. He added: 'To achieve the pass rate we have to employ strategies that ensure youngsters are as motivated as possible. We are talking about two or three youngsters a year who need encouragement in two or three subjects.'
But Don Allen, chairman of Hampshire CC's education committee, said it was the first time he had heard of deposits being taken. 'It seems a bit heavy-handed,' he said. 'I can understand the motivation but some families might not be able to stump up the money. I shall be asking my officers to look into the matter.'
But the Secondary Heads Association gave guarded support to the scheme. A spokesman said it was not uncommon for schools to seek payment from parents for missed exams. 'It is not easy to get the money after the exams and I can see the logic in making a move like this,' he said.