A British nursery worker on Wednesday pleaded guilty to sexually assaulting young children in his care and filming the abuse in what London police described as one of its most harrowing investigations.

Vincent Chan, 45, admitted sexually abusing four girls, who were aged between two and four years old, between 2022 and 2024 while working at a nursery in north London, offences which prosecutors said were “a heinous breach of trust”.

He pleaded guilty at London’s Wood Green Crown Court to 26 offences, including five counts of sexual assault by penetration and four counts of sexual assault by touching.

Chan also admitted 11 counts of taking indecent images, relating to the children he abused, and six counts of making indecent images, relating to thousands of other abuse images found on his devices. He will be sentenced in January.

London’s Metropolitan Police said Chan’s offending came to light after a colleague reported him for suspected child cruelty after he had been capturing what officers said was “disturbing footage” of children.

Detectives said Chan’s guilty pleas followed “one of the most harrowing and complex child sexual abuse investigations” the force had ever undertaken.

Detective Superintendent Lewis Basford, who led the investigation, said Chan’s offending spanned years, and revealed a calculated and predatory pattern of abuse.

“He infiltrated environments that should have been safe havens for children, exploiting the trust of families and the wider community to conceal his actions and prey on the most vulnerable,” Basford said in a statement.

Some of the families of children who attended the nursery said it had failed them.

“As parents we are still trying to process the sickening discovery that our children were subjected to despicable abuse by Vincent Chan,” they said in a statement.