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Serious concerns about a suspected paedophile childcare worker were ignored for months by nursery managers, a BBC investigation has been told.
A former employee at Partou King Street Nursery in Bristol says she alerted management to Nathan Bennett's behaviour before it was discovered he had been abusing children.
Bessie Martin told bosses that Bennett would hold children for too long, she says, often sitting them on his lap out of view of CCTV. Her concerns were dismissed, she says, and she was told she was "imagining it".
Bennett was sentenced to 30 years in prison in February for sexually abusing five boys aged two and three.
Partou has told the BBC it "actively encourages" reporting of concerns and has implemented recommendations to "strengthen safeguarding governance further and enhance oversight across the organisation".
Although the King Street nursery closed last December, Partou is one of England's biggest nursery providers with more than 100 sites.
The BBC has found more Partou nurseries were given official notices to improve safeguarding, safety or welfare than the average in England after Bennett's arrest.
Another chain, Bright Horizons - which runs 270 UK nurseries - also received a higher than average number of Welfare Requirements Notices (WRNs) from the regulator Ofsted, following the arrest of another paedophile, Vincent Chan, in London.
Before the arrests of Bennett and Chan, the figures for both nursery chains were much closer to the national average.
Ofsted has told the BBC it increased its inspection work into Partou and Bright Horizons after both cases emerged.
Bessie Martin says she became suspicious of Bennett's behaviour when she saw him holding on to children for too long.
"I would see a child try to wriggle away or stand up and walk off, but he'd say, 'sit here and we're going to read a book'."
She was "constantly complaining" about him for months, she says, and it was only after she filed a whistleblowing report to the chain's senior management that he was suspended.
However, Bennett was allowed to return to work shortly afterwards. Two weeks later, a review of CCTV showed him putting his hands down a boy's trousers.
The nursery suspended Bennett again and informed the council's Local Authority Designated Officer (LADO). Police were alerted the following day and he was arrested.
We have also heard from parents who reported Bennett's behaviour to nursery management in the months before his arrest. "Overly physical" with children, is how one mother described him.
Some of these concerns were not passed on to the LADO and Ofsted, even though the nursery was legally required to do so, our investigation has found.
Limited CCTV evidence means some parents will never know if their children were abused. Speaking out for the first time, another mother says her child told her Bennett had "tickled" him inappropriately under his clothes.
The paedophile often worked alone in the mornings when children arrived, she says.
"I've got an image of seeing [my son's] little face at the window, sometimes crying, and Nathan [Bennett] beside him waving."
Partou nurseries were twice as likely to get a WRN from Ofsted than the average nursery in the four years to March 2025, our investigation found. But that rose to more than seven times more likely in the following 12 months, after Bennett's arrest.
Welfare Requirements Notices can cover a range of issues - including a nursery failing to report allegations of abuse, unsafe premises, poor record-keeping and inadequate staff vetting.
Partou told us such figures must be interpreted carefully, as different operators may apply varying standards. Safeguarding is its "highest priority", it said, and it has provided affected families with the "fullest possible support".
An independent safeguarding review had identified failures by individuals at the Bristol nursery, it added, and some no longer work for the company, while others remain subject to ongoing internal actions.
When he worked at Bright Horizons in West Hampstead, Vincent Chan was "very cold and didn't show any emotion", a former staff member who wants to remain anonymous told us.
She believes he should not have been working with children, however she did not formally complain.
The paedophile was jailed for 18 years in February after abusing children there and elsewhere over seven years. He used nursery iPads to film his crimes.
The nursery was "not a good place", the former staff member added, citing a high turnover of agency staff who, she said, did not engage with children.
Bright Horizons told us there is no indication others working at the nursery were aware of Chan's crimes.
However, the company is now facing legal action from 46 families who claim it dismissed their concerns about Chan's general behaviour - including shouting at children and encouraging them to be aggressive with each other.
The minimum parents should expect is for their children to be kept safe, says Alison Millar from legal firm Leigh Day.
The number of WRNs Bright Horizons received last year is also very concerning, she adds.
From March 2021 to March 2025, Bright Horizons nurseries were getting WRNs at the average rate for England, we have found. But in the following 12 months, this rose to more than four times the average, because of Ofsted's increased inspection work.
Bright Horizons said it welcomed scrutiny and did not consider the BBC's data analysis to be an "accurate representation of the standard of care" in its nurseries.
It expanded training, engaged an independent safeguarding organisation to review practices, and was piloting the use of cameras, it added.
The overall Ofsted rating at both Partou's King Street Nursery and Bright Horizons in West Hampstead ratings was "good" prior to the arrest of either paedophile.
The regulator gave the Bright Horizons site another "good" rating after Chan's arrest, but before his offending was revealed.
Ofsted ratings can be "dangerously misleading", says Dr Tammy Campbell, of the Education Policy Institute, because they may not reflect the number of complaints, concerns or WRNs a nursery could have.
"It's possible for a setting to have an Ofsted rating of 'good' and to be completely failing," she says.
Most of England's nurseries (98%) are rated "good" or "outstanding".
Even if concerns are raised in between routine inspections every four years, performance ratings are usually retained.
Wales, Scotland and Northern Ireland have separate regulators.
Ofsted says it will work with government to strengthen its response to concerns in nurseries, adding its new approach is "much more rigorous".
Neil Leitch, chief executive of the Early Years Alliance which represents childcare providers, says the "vast majority" of nurseries are safe, but recent months had seen a "disproportionate number of concerns".
His organisation is focusing on removing bad practice, but government investment is needed to reduce pressure and improve staff training, he says.
Early Education Minister, Olivia Bailey, says the government has implemented tougher recruitment checks, clearer whistleblowing procedures and new training standards.
If you would like to contact BBC Journalist Hayley Hassall about this story you can email her directly at Hayley.Hassall@bbc.co.uk
Additional reporting by Maryam Ahmed and Barbara Metzler, BBC Verify
