pasted from elsewhere
Can I take photographs of children?
Photographing children in public places is, for most children, exactly the same as photographing adults under the same circumstances. That is, there is no right to privacy and hence it is legal.
The exception is children (and vulnerable adults) who are wards of court or subject to a child protection order, or on the 'at risk' register. The Children Act 1989 creates special rights of privacy ('the rights of the child') which make it an offence to publish any photo that might place them at risk from, say, an estranged violent parent by divulging their location. A photograph of a child in a public place wearing school uniform, or accompanied by others whose whereabouts are known to the would-be assailant, might conceivably do this.
The Children Act is also the cause of problems at sports clubs and similar venues, as the supervising adult has a legal duty to safeguard these enhanced rights to privacy. And since part of that right is confidentiality about the child's status, usually they will not know themselves which children in their charge the Act applies to. Their safest course of action then becomes one of challenging any photographer as an imminent threat.