A FORMER headteacher at a South Wales approved school has demanded a time-limit is put on allegations of abuse.The man said it was impossible for former teachers and carers to disprove allegations that they had abused youngsters in their care up to 30 years ago.The former head, who has asked not to be identified, has more than 25 years’ experience in approved and special schools’ service. He has not been subject of any allegations himself.But he claims police “trawling” inquiries will eventually be exposed as “a massive miscarriage of justice, unique in the annals of the British judicial system”.These investigations – which are being carried out by many forces in England and Wales – look at allegations of abuse at child care institutions, such as children’s homes and approved schools, going back as far as the 1960s. They involve police officers visiting and revisiting people who were once in care and asking them if they ever experienced problems….