Paedophile teacher Nigel Leat was able to film himself abusing young girls in his classroom because the school's bosses failed to act on his increasingly sexual behaviour, an independent report revealed today.

Leat, 51, was described by a judge as a "paedophile of the most sickening order" when he was jailed indefinitely last year after abusing five girls - some as young as six years old.

Leat, of Bloomfield Road, Bristol, admitted 36 offences, including attempted rape of a child and sexual assault on children. Police also found more than 30,000 indecent photographs on memory sticks.

Senior managers at Hillside First School in Weston-super-Mare, Somerset, had repeatedly been told of Leat's inappropriate behaviour by fellow teachers but failed to act.

The school's own management report notes at least 30 incidents of Leat's "inappropriate or unprofessional conduct" - but only 11 were recorded formally within the school.

These included Leat taking photographs of pupils on his mobile phone, of kissing and cuddling them and even having an erection while sitting on cushions in the library with one pupil.

In another incident, a teacher saw Leat in his underpants and a T-shirt while getting changed in his classroom.

When one teacher reported Leat after finding photographs on a school camera of a girl posing with him, she claimed she was told "not to insinuate things".

Another teacher was told that she "should not accuse him of things" after raising concerns.

Leat had his "favourites" and the girls he picked were frequently less academically able, emotionally needy, vulnerable or pretty.

He was "over-familiar" and would speak to and joke with students in a manner that was "inappropriate", the report found.

Staff were "sufficiently concerned" about Leat's behaviour to ensure that his favourites were moved to other classes, yet the teacher continued to work at the primary school for 15 years.

The married father of two's abuse only came to light in December 2010 when one of his victims told her mother that Leat had been sexually assaulting her almost daily for the previous two months. The girl's mother called police and Leat was arrested.

The shocking catalogue of failed opportunities to tackle Leat was revealed in a serious case review published today, which made 35 recommendations for improvement.

The North Somerset Safeguarding Children Board commissioned the report following the pervert's arrest.

The report identified 20 pupils who were witnesses or victims of abuse committed by Leat and said his behaviour was "typical of the grooming" perpetrated by paedophiles.

Leat joined the school in September 1995 as a newly-qualified teacher, having previously worked as a musician and music teacher.

"Within a year of his appointment and throughout the time that he worked in the school, a number of teaching and support staff in the school had a variety of concerns about the teacher," the report stated.

"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.

"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.

"The management report from the school makes reference to at least 30 incidents of inappropriate or unprofessional conduct involving the teacher.

"These ranged from inappropriate lesson content, through over-familiarity with children to indecent touching.

"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.

"There is a substantial body of evidence that points to the fact that the concerns about the behaviour, teaching practice and relationships of the teacher were not appropriately dealt with.

"It was well known in the school that (Leat) had favourite pupils that he gave special attention to and with whom he developed close and inappropriate relationships.

"It is now known that (Leat) told children that they must keep things secret, which made disclosure to parents less likely."

The report said that although Hillside First School was identified by Ofsted as academically successful, it had not been matched by a culture of safeguarding and it blamed the management style.

Senior management also failed to notify the school's governors or the local education authority with the concerns that had been raised about Leat.

"Much of the behaviour exhibited by the teacher was typical of grooming activities pursued by adults intent on sexually abusing children," the report stated.

"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 process of reporting and acting on concerns was positively hindered by a management style that discouraged comment and open communication."

The serious case review added: "The clear lesson emerging from this review is that it is not sufficient for a school to have a culture that focuses only on attainment.

"A school culture needs to recognise that if children are to achieve their potential they must first be assured of a safe environment, in which any risks that they may face will be given full and open consideration by staff at all levels in the organisation.

"It must also be recognised that it is very rare for a teacher to commit offences in the manner of (Leat).

"However, some of the allegations were of such a serious nature, particularly those from children themselves, that they constituted matters that should have been investigated under the child protection procedures."

The school's staff also raised concerns about Leat's competence, with him often being ill-prepared for lessons and his teaching lax and uninspiring.

Last month headteacher Chris Hood left his post, having been suspended since the previous January.