As I understand it, IF it turns out that the Data Protection Act requires permission (and 'they' haven't decided yet) then it won't just be for kids, you'll have to get permission from everybody you take photos of. The only difference with children is that they're not allowed to give permission themselves, their parents have to do it for them.
So all these schools and clubs saying you need permission from all the parents aren't actually covering their asses in any way, shape or form because if the DPA starts applying to photography in the way we're all discussing, those schools and clubs will only have permission for the photos of kids, when what they'll really need is permission from everyone, regardless of age.
Sorry that's longwinded but it's the most concise I can actually say it clearly.