Officers visited a school today after another email was sent to parents warning their children to be vigilant after reports of a man taking pictures of a pupil.

Rickmansworth School in Croxley Green says it was informed of a man allegedly taking pictures of a girl outside All Saints’ Church in The Green yesterday morning (Monday), while he was sat in a white van.

Last Wednesday, police received a report that a 13-year-old boy was approached by a man while he was on his way home from school in Scots Hill, Croxley Green.

He was reportedly offered a lift in a white Transit van but the schoolboy refused.

There were a spate of reports in late October that pupils had been approached in and around Watford and Hemel Hempstead and police pledged to increase patrols around schools.

In the latest email home to parents, Rickmansworth School said: “We have been informed that a man slowed down in his white van to take photos of a student outside All Saints’ Church while they were on their way into school this morning. We have informed the police of this matter.

“We therefore request that you discuss your journey your child takes to and from school. Please also remind your child not to engage in conversations with strangers and be alert at all times. Where possible, students are encouraged to travel in pairs and should call 999 if they are approached bu a stranger or feel threatened at any time.”

Police say they have followed up every report they have received and where possible, spoken to the men they believe to be involved.

Detective Inspector Mike Hanson has stressed the force are “confident” these men are not preying on schoolchildren.

He said: “We have followed up every report of suspicious activity in relation to local students and where possible have spoken to the men believed to be involved. In all of these cases they have been able to easily explain their behaviour and we are confident that these men are not preying on schoolchildren.

“Following several messages that have been sent out to parents from Rickmansworth School, we have visited the school today to address their concerns.

"Although we would always advise people to remain vigilant, report any suspicious behaviour and follow general personal safety advice, we’d like to reassure the local community that there is no increased risk to their children.”