Lee Hargrave, 49, of Egham in Surrey, set up the spy camera to take photos of a victim who was aged between 14 and 15.
He pleaded guilty to voyeurism and creating indecent images of a child but denied having any sexual attraction to children, coming up with a litany of excuses for his behaviour.
In July he was given a 13-month prison sentence suspended for two years – meaning he would not see the inside of a cell unless he breached the terms of his sentence.
In September the Solicitor General referred the case to the Court of Appeal on the grounds that the sentence was “unduly lenient”.
But appeal judges rejected the application, stating that the judge applied the correct sentencing guidelines for the length of the offence.
They further stated that the sentencing judge was within their rights to suspend the sentence as there was evidence of a “real prospect of rehabilitation”.
Hargrave will remain on the Sex Offenders Register for life and was given a 10-year Sexual Harm Prevention Order.
He resigned from the Met Police in August 2024.
A misconduct hearing the same month decided he would have been dismissed without notice had he not resigned.
Hargrave is now on the Barred List for policing.
