The harrowing reports of Sara Everard's rape and murder and the conviction a few weeks ago of John Humphreys create an awareness of the dangers around us. After allowing raw emotions to quieten down, I am remembering past experiences.

Many years ago, my church in Berkshire asked me to guide the formation of policy for the safeguarding of children and vulnerable adults. This made me aware of the issues in some detail which the recent news has brought back into sharp focus.

An expert then commented "in a parish as large as yours, you should expect to have been targeted by four paedophiles". This has rung in my ears ever since, with the implication that there are people with perverted fixations on sexual abuse, physical abuse and maybe even killing, who strive to get into positions from which they can satisfy their evil cravings. As and when such people are caught, all those around them are usually completely surprised and shocked; evil doers obviously take great care to keep their intentions secret!

Police "DBS" checks only flag people with a previous history; relying on this as a test of suitability is totally misguided; the most worrying perpetrators take great care not to have a history.

Many years ago, when I lived in Reading, the police called after a man was reported exposing himself in the park opposite and was thought to have run into our garden. We searched outside the house and in the back garden and found nothing. A couple of days later, a small hole in our back hedge, which had been used by children, was suddenly blocked up. It doesn't take a rocket scientist to imagine that the culprit blocked it to remove evidence of his escape route. That is exactly the type of small signal which should be reported.

People do exist with perverted fixations of sexual and physical abuse and maybe even killing. Fortunately very few, but these people work hard to get into positions of responsibility where others will feel confident around them. Groups with vulnerable potential victims make special targets, most obviously schools, youth and sporting activities, including church groups, all of which nowadays have established "safeguarding" policies.

Organisations giving people authority, such as the police, church ministry, sports coaches, schools and political positions can be platforms for abuse, attractive to people with evil intent. For example, in the Food Bank, people have offered to do deliveries and nothing else which would allow personal contact with vulnerable people. The Food Bank has always rejected such specific offers.

We all need to be alert that real evil does exist secretively among us, even locally - not widespread enough to make us nervous, but real enough to be watchful for people whose behaviour and desires are not normal. Social media can be used to share evil ideas in private. We are told the murderer of Sarah Everard did just that, including other police officers who are now rightly being investigated. Anyone failing to report such a group is surely at fault and probably committing a formal offence. Our wonderful communications and social media carry serious dangers as well as benefits; we all need to be watchful.

We are all on this planet together; we should all be one family, not afraid to pick up on offensive behaviour and stand up against it, as we might within any family.