The chief constable of Cambridgeshire Police has admitted he would take “a more severe sanction” about allowing an officer to return to work after being caught using a spy pen to take “up skirt” images of children in Tesco.

Police officer Nick Lidstone was this month jailed for admitting a string of child rape and sex offences but the court heard that he kept his job eight years ago despite being caught taking images using a spy pen.

Cambridgeshire chief constable Simon Parr said: “At the time of the offences in 2005, the case was reviewed and the then-deputy chief constable decided Lidstone be placed on restricted duties.

“If we were faced with the same decision today, a more severe sanction would be imposed.”

During the hearing, in which the jury heard that Lidstone groomed his nine year old victim, Judge Anthony Bate was incredulous that Lidstone had remained a police officer.

He told the court: “Why on earth you were not charged under the sexual offences act, I do not know.

“Whoever took that decision, it allowed you to carry on as a police officer.”

Following the Tesco spy pen incident Lidstone received a conditional discharge.

He pleaded guilty to a public order offence, but because it is not a sexual offence his name was not placed on the sex offenders register.

As part of his agreement he began counselling - but all of his most serious offending happened in the years afterwards.

This month at Norwich Crown Court Judge Bates sentenced Lidstone to 14 and a half years behind bars after the 54 year old confessed to 13 offences that included three counts of rape, three of indecency with a child, various sexual assaults and taking an indecent photograph of a child.

He was arrested on June 26 this year and dismissed for gross misconduct on December 9 by the Chief Constable.

The court heard that Lidstone groomed his victim, who cannot be named for legal reasons, by exposing himself to her, showing her pornography and taking indecent photographs.

One witness who knew the victim said her life had been ruined by his behaviour.

Deputy chief constable Alec Wood said: “The sentence handed out reflects the horrendous nature of Lidstone’s crimes, which were committed over a prolonged period of time.

“We want the public and our own employees to feel confident about raising concerns about the conduct of our officers and staff. We will always investigate these cases thoroughly and ensure any offenders are brought to justice.”