A child protection charity has described an alarming incident where a mirror was placed under the changing cubicle of an 11-year-old girl as "relatively rare".

Last week, it emerged that an 11-year-old girl had alerted police after a noticing a mirror being placed under her changing room cubicle at William Penn Leisure Centre, in Shepherds Lane, on Tuesday, January 13.

But Jon Brown, NSPCC lead on tackling sexual abuse, told the Watford Observer, that while this type of event is "relatively rare", people should remain vigilant and praised the girl for contacting the police.

No arrests have been made by officers investigating this incident.

Mr Brown said: "This incident is alarming and of course frightening for the girl and she did the right thing in contacting the police. People in the community should be alert to people behaving suspiciously where there are children and report any concerns to the police.

"Incidents of this kind are thankfully relatively rare, with most abuse taking place within the family environment.

"If people are concerned about their sexual thoughts about, or behaviour towards children, they should seek help from the NSPCC or Stop it Now helplines."

Mr Brown added there are a number of ways of combating sexual abuse, but stressed the importance of education in dealing with it.

He said: "It’s all about public awareness and alertness and recognising that we all have a role to play in protecting children.

"This means good quality information for parents about how sexual abuse occurs and about how abusers operate and it means good quality relationships and sex education at school so that if children are worried they know what to do and who to tell."

Staff at William Penn Leisure Centre have confirmed there no plans to change the "mixed-sex changing room" at the centre.

People using the sports centre have access to individual changing cubicles.

Paul Christie, regional manager at Hertsmere Leisure said: Paul Christie, Regional Manager, Hertsmere Leisure, said: "We are treating this incident extremely seriously and are actively working with Three Rivers District Council, who own the venue, and the Police.

"There are no plans to change the Centre's changing facilities. However, we keep our facilities under regular review and in light of this incident we have increased our staff patrols of the changing rooms and our staff are being extra vigilant."