Skin_deep has explained why they posted. And if they hadn't done, and then something untoward happened, how do you think they would feel? Do you honestly think it would be better to have used up scarce police resources by dialling 999 on the basis of an uncomfortable feeling? Or to "confront" the man in question themselves? What would they say? I don't feel comfortable with you watching the children for so long when you don't seem to be with any of them? I was once in a similar situation in the playground in Brockwell Park, although in this case the man in question appeared to be possibly taking pictures of the children on an iPad, whilst ostensibly sitting on a seat in the playground "reading" the iPad at an angle. He wasn't with any children. Two community police officers appeared, and he put the iPad in his bag, but they didn't approach him. I wasn't able to talk to them because I was with two small children on the other side of the playground, and I couldn't leave them alone. I've always regretted not in some way doing something, particularly as I assume the police were there for a reason. If that had been a park more local to me I might well have posted something on here. Many playgrounds have notices up saying that adults are not allowed unless accompanied by children. I don't know whether the one in Ruskin Park has? It's a bit of a stretch to call posting on here starting rumours or curtain twitching. I'd say it was a reasonable action from somebody who felt sufficiently uneasy about a situation to share their unease and explain why.