Families affected by a former nursery worker who sexually abused young children in his care want an investigation after learning he was allowed to return to work despite a complaint having been made against him.

Vincent Chan, who worked at Bright Horizons nursery in Camden, north-west London, between 2017 and 2024, was jailed for 18 years in February after admitting 56 sexual offences.

Concerns about him were raised in 2021, according to reports. The nature of the complaint has not been made public.

Camden Council said it had shared "all relevant documents", while Bright Horizons said it could not comment while the review was ongoing.

An investigation by The Guardian said Bright Horizons had investigated concerns about its own employee with oversight from the council, but the matter was not referred to the police.

In a statement, more than 50 of the affected families who are taking legal action against the nursery, said: "We need a full and independent account of what happened, who knew what, when they knew it and why these decisions were made."

Simultaneously, an independent local Child Safeguarding Practice Review (CSPR) is under way, with findings expected to be published in early 2027.

Speaking anonymously to the BBC, parents of one of the nursery victims, Andy and Sarah (not their real names), said they had "only just learned" about the complaint, and that they were "shocked".

"We think this was an opportunity to stop this man and his vile behaviour, years before this happened to our children," Andy said.

"We're angry. We're angered by the fact this has potentially been missed or overlooked."

Warning: This article contains distressing details

Chan was first reported to police by the nursery in May 2024.

A colleague had raised concerns about his activities with the children, which included Chan filming a child falling asleep and setting the footage to music.

He was first arrested on suspicion of child neglect, but searches of his electronic devices led officers to discover his sexual offending: he had filmed himself abusing young children at the nursery, and had also amassed a collection of at least 26,000 indecent images online, including clips of children being raped.

During Chan's sentencing, Judge John Dodd KC told the court that Chan was a "perverse and depraved" man who had "clearly lost all sense of moral compass".

Andy and Sarah said their son was now living with post-traumatic stress disorder (PTSD).

Sarah said experts were sure he witnessed physical abuse.

"We know that he was asked to partake in physically hurting other children.

"In videos, where the boys are being hurt, Chan would ask our son to hit, kick and spit on the other boys."

"Our son didn't nap at nap times, and we know Chan committed a lot of his sexual offences on the girls whilst they were sleeping," said Andy. "We're quite sure our son witnessed this abuse."

He added: "Some of the language our son uses is of someone who has witnessed abuse."

Sarah said when she learnt of Chan's crimes she was "in complete shock".

"I have looked at this man in the eyes for years, I have handed my child over to this person. This is the sort of predator you see in movies. It was disbelief that we've all been in such close proximity to someone who was so evil," she said.

Sarah added their grief and anger were now being channelled into fighting for changes to the national nursery system to protect children in the future, including installing CCTV in every nursery room, and a national reporting system for parents and whistle-blowers, as well as a strict policy on digital devices in nurseries.

Alison Millar, a solicitor representing the victims' families said: "Our clients have to live with the continuing uncertainty as to what their children may have experienced or witnessed.

"They require - and deserve - urgent answers to their questions as to what was known about Chan in 2021 and how he came to be cleared to return to work with their children."

Millar added that the newspaper's report strengthened the case for a criminal investigation against Bright Horizons.

"Our clients are calling on Camden Council as the responsible authority to ensure there is an investigation into whether offences were committed under the health and safety legislation," she said.

In a statement, Camden Council said its Local Authority Designated Officer (LADO) provided advice to Bright Horizons, after the nursery informed them of a complaint.

It said "all relevant documents and information" had been shared with the independent CSPR team and that it was "ready to receive the review's recommendations once it is published and take action".

"In the meantime, we are committed to making continual improvements to safeguarding. We are determined to make a real and tangible impact on national safeguarding arrangements for the future."

Bright Horizons said it "remained appalled by Vincent Chan's crimes, and our thoughts are first and foremost with the children and families affected".

In a statement, it said it "strongly encouraged parents to share all their concerns" with the CSPR.

"As the review is ongoing, we are unable to comment without the express written authorisation of the committee, as we do not wish to prejudice that process. We have sought that authorisation and will respond as soon as we are able.

"When any concern is raised, our policy is to take it seriously and act on it, including referring it to the relevant authorities where appropriate.

"We have and have always had a dedicated complaints team, separate from our nursery teams, and a procedure for escalating concerns beyond nursery level. We encourage any parent with a concern to raise it with us."

If you have been affected by any of the issues raised in this story, information and support is available via BBC Action Line.