A primary school teacher who filmed himself sexually abusing young girls in his classroom was today described as a \"paedophile of the most sickening order\" after being jailed indefinitely. An independent serious case review has been commissioned to establish if authorities could have acted sooner to prevent Nigel Leat sexually assaulting the pupils in his care, the youngest of which was six-years-old, over the course of five years. Leat, of Bloomfield Road, Bristol, last week admitted the abuse of five girls and pleaded guilty to 36 offences, including the attempted rape of a child and carrying out sexual assaults on children. The 51-year-old was today given an indeterminate sentence and will serve at least eight-and-a-half years for the abuse which happened at Hillside First School in Weston-super-Mare, Somerset. Detective Superintendent Geoff Wessell, of Avon and Somerset Police, said Leat had \"preyed on the children\" and \"abused them in the most sick way\". The public gallery at Bristol Crown Court was full as relatives of Leat\'s victims watched him being sentenced. The families listened in disbelief and sobbed as they heard Judge Neil Ford QC outline the shocking details and extent of Leat\'s actions. Judge Ford told Leat: \"Your manipulation of the children was clever, cunning and insidious. It was also wicked.\" The father-of-two, who had worked at the school for 15 years, wore dark glasses and sat with his head bowed starring at the floor in the dock as he was sentenced. The judge added: \"I am of the opinion you do represent a serious risk to young girls. These offences were carried out over a long period of time with great regularity. \"You have the ability to befriend young girls and persuade them to participate in sexual behaviour.\" The judge said Leat had told a psychiatrist he was unable to stop. \"You told him you couldn\'t stop, you couldn\'t think of anything else but to take your camera to school and make films. You described it as an obsession,\" he said. \"You were in a position of authority and trust. You were able to carry out repeated abuse. No members of staff or parents suspected that you were conducting this abuse. \"You carried out a catalogue of abuse at a place where children were expected to be wholly safe,\" he added. The court heard details on Friday of how Leat would molest the girls as they practised their reading aloud in class, getting them to perform sex acts on him at the same time and filming the abuse. Police revealed that Leat used to identify \"star pupils\", referring to them as \"sweetie pie\" and darling\" and showering them with gifts before abusing them in one-to-one reading sessions. Videos, which were up to 10 minutes long, showed the abuse took place in the school\'s staffroom and a resource room. He also wrote sickening letters to them, describing what he wanted to do and asking them to perform sex acts on him. In the letters the children can then be seen to reply. Leat initially denied all the claims against him, but confessed after police found the films on his home computer. After police arrested him on December 13 last year, they discovered about 30,500 indecent photographs and 720 indecent movies in his possession. Speaking outside court Mr Wessell, the senior investigating officer on the case said: \"Nigel Leat is a predatory paedophile of the most sickening order who has preyed on the children of his school and abused them in the most sick way.\" He added it was the \"worst breach of trust\" he had ever come across in his career and paid tribute to his victims who had come forward and ensured \"Leat will stay in prison for a long time\". North Somerset Council revealed there would be an independent serious case review and an ongoing disciplinary process following the suspension of the head teacher at Hillside First School. The council added in a statement: \"Nigel Leat\'s sickening actions have had a devastating impact on the victims, their families and everyone connected with the school. \"Since his arrest in December, our educational psychologists, social workers and other staff from North Somerset Council have been in the school regularly supporting children, parents and staff.\" The council said the local Safeguarding Children Board decided in January to commission an independent serious case review to examine the circumstances around what had happened and if action could have been taken earlier that would have prevented abuse. The review is expect to be completed by early autumn. During the course of joint investigations with the police, the council said concerns had been raised about leadership and management at the school, which had led to the suspension of head teacher Chris Hood in January. The council added a disciplinary process is ongoing and likely to conclude next month, but was keen to highlight there is no police involvement in the process and no ongoing investigations of any other members of staff at the school. The abuse had gone undetected at the school until December last year when one victim told her mother that Leat had been touching her.