A £13,000-a-year school in Twickenham had a man on probation after a seven-year sentence for a violent crime working on the premises “while children were still there”.

Elliott Sheppard, 25, who is identified as “high risk” to the general public but “low risk” to children, was hired by the Mall School’s contracted cleaning company Walker’s in December.

He claimed they allowed him to start the day after his interview without doing proper checks.

Mr Sheppard said: “During the interview I told them I had been in prison but they said that was ok, only that I might not be able to come in until 6pm when the kids are gone- but the kids aren’t always gone by then and they didn’t enforce that anyway.

“No one was checking on me while I was there.

“There was a manager but she would walk around.

“I’m no danger to children, but they didn’t check my record so it would be easy for someone who did to get a job there.

“It’s really bad, especially for a school that parents pay so much for their children to go to.”

Mr Sheppard, who no longer works at the school over an issue with pay, said after school clubs went on past 6.30pm.

A spokesman for the preparatory school, for boys between four and 13, said when someone’s work at the school is identified as “regulated activity”- where that person could come into unsupervised contact with children- “then a Disclosure and Barring Service (DBS) check is carried out”.

This checks for previous convictions and whether or not the person is barred from working with children.

The spokesman said: “Under the safeguarding regulations, individuals are permitted to start work at a school before a DBS certificate has been received as long as a risk assessment has been carried out and appropriate safeguarding measures have been put in place.

“As a DBS check for Mr Elliott Sheppard had not been received before he commenced work at The Mall, he was informed that he was not allowed to come onto the school site before 6pm.

“Walker’s Facilities Management Services have confirmed that he did not come onto the school site before 6pm and he was supervised while he was on the school premises.”

Walker’s alleges Mr Sheppard did not disclose his criminal conviction during the interview but Mr Sheppard, who said they told him he might not be able to work before 6pm, denies this was the case.

He said: “How would I have known about the 6pm time if I didn’t tell them about my criminal conviction?”

Mr Sheppard also alleges the cleaning company rang him to say the Richmond and Twickenham Times “wouldn’t be doing this silly story”.

The Mall spokesman said: “Despite the checks that were put in place, the school will be carrying out its own investigation to determine if there are any lessons to be learnt and will be sending a report to the Charity Commission.”

He added: “Thank you for bringing this matter to our attention.

“The school takes its safeguarding responsibilities extremely seriously which include a series of rigorous pre-employment checks before anyone can work at The Mall in either a paid or voluntary capacity.

“This applies both to individuals employed directly by the school or by third party contractors.

“An independent audit of the school’s safeguarding measures was carried out by inspectors from the Independent School’s Inspectorate in June 2017.

“The report, which is available on the school’s website, indicated that all the relevant safeguarding measures are being met.”