So what was so very very hard about asking permission first - or at least explaining who they were? Sounds like they were a group of camera club members with more than likely flashy pro-looking cameras, taking pics at the side of the youngsters' rugby pitch. With no connection to the group at all.
Sorry, more than likely if it was my son in the group I'd want to at least know who they were, and why they didn't have the good manners to ask first.
Sounds like if they'd done so, the whole incident (and petition) may well have been avoided.
Isn't it time photographers grew up?
Adding more (then I've said enough!)..... I don't do much 'documentary' photography as such, but I am often out and about with my camera in London, and I have never, ever experienced any problem or paranoia. Most often people, if they notice me at all, are interested in my camera and more interested that their children - if they are around mine - are getting in my way, rather than that their children may be included. Sometimes I find myself worrying about other people worrying what I'm doing but can honestly say I've never had any evidence of this, (so paranoia - photographers' paranoia that is - must be catching!)
It's surprisingly easy to make some sort of contact with people if you want to photograph near them, you don't even have to have a full conversation.
It wouldn't cross my mind, though, to photograph youngsters in this sort of group situation without talking about it first - when I was studying photography full time and had to do the 'documentary' module getting permission if at all possible & reasonable (it isn't always) was drummed into us as good practice. That's regardless of who it is you're photographing.
). Any crackpot (no reference to current discussion) can put up a petition about ANYTHING and urge people to sign it. There is usually very little information indeed, and even blatant misinformation.