A teacher was able to film himself abusing young girls because of a \"lamentable failure\" by school management, a review has found Nigel Leat, 51, was jailed indefinitely for abusing children at Hillside First School in Weston-super-Mare. At his trial, which heard Leat abused five victims, some as young as six, the judge described him as a \"paedophile of the most sickening order\". The serious case review was commissioned after Leat\'s 2010 arrest. Leat, of Bloomfield Road in Bristol, admitted 36 sexual offences at Bristol Crown Court in May last year. Thousands of images The charges included one count of attempted rape, 22 of sexually assaulting a child under 13 and eight of sexual assault by penetration. Police also found more than 30,000 indecent photographs on memory sticks. The offences were committed between September 2006 and December 2010, when Leat was arrested. A report carried out by Leat\'s school while he still worked there referred to at least 30 incidents of \"inappropriate or unprofessional conduct\" involving the teacher. Hillside First School gates The abuse happened at Hillside First School in Weston-super-Mare The serious case review, commissioned by North Somerset Safeguarding Children Board, said the incidents in the school management report ranged from indecent touching to inappropriate lesson content and over-familiarity with children. \"On a number of occasions colleagues advised the teacher of the inappropriateness of his behaviour and pointed to the risk that he could be accused of professional misconduct,\" the review said. \"However, only 11 of the 30 recorded incidents were reported formally within the school.\" The incidents included Leat taking photographs of pupils on his mobile phone, and kissing and cuddling them. A teacher also saw Leat in his underpants and a T-shirt while getting changed in his classroom. \'Common knowledge\' Leat joined the school in September 1995 as a newly-qualified teacher. The case review said a number of school staff had \"a variety of concerns\" about him within a year of his appointment and throughout the time that he worked there. \"Early on it was noticed that the teacher had favourite pupils within his class who were invariably girls, who were often given tasks within the class which were viewed as privileges as well as being given greater personal attention by the teacher,\" the review said. \"These pupils were allowed to be over-familiar with the teacher, who was known to speak and joke with his pupils in a manner which was inappropriately adult. \"This situation was described by staff to have been common knowledge amongst the school staff.\" \'Grooming activities\' The review identified 20 pupils who were witnesses or victims of abuse by Leat. It added: \"Much of the behaviour exhibited by the teacher was typical of grooming activities pursued by adults intent on sexually abusing children. \"The failure of school managers to take action in response to the concerns raised was compounded by the failure of anyone in the school to recognise that the teacher\'s behaviour might have constituted grooming for sexual abuse. \"This raises questions about the impact of the safeguarding training that staff in the school had received.\" The review\'s 35 recommendations include that the North Somerset Safeguarding Children Board should ensure the review is sent to all schools and early years settings in the area, along with the Ofsted publication \"Safeguarding in Schools: Best Practice\". Leat was given an indeterminate sentence with a minimum tariff of 24 years. He will serve at least eight-and-a-half years before he can be considered for parole. Last month the school\'s headteacher Chris Hood left his post, having been suspended since January 2011.