Would I let a 7 year old walk 20 yards on their own? Or run ahead for 25 yards? Would I keep them on an extendable lead to prevent them going too far? Or let them walk a km on their own? It doesn't actually matter exactly what I or you would do, it's a question of whether not following a societal norm in such matter is worthy of involving the State machinery.
If I beat my child senseless every saturday - then yes, involve the State, no question.
If I live a picture postcard white middle class home counties life, never doing anything (and never permitting my children to do) anything which might be remarked upon by anyone we encounter as eccentric, either in our home or out of it - then of course noone would consider involving the State.
But where do you draw the line? Are we really arguing over whether 200 yards is ok but not 1km? Or, in even having the argument, is there an underlying assumption that this woman has crossed the line into no longer being assumed to have the best interests of her children at heart, and to be responsible to decide, with them, what sorts of risks are ok for them to take?
I want to know exactly where that line is supposed to be. Lots of people parent in ways I find distasteful, sad, counterproductive, unkind to their children, but I still respect their right to privacy in family life, in the absence of the sorts of abuse we would all agree are illegal. I don't think we should be calling social services on other people, or that they should act on phone calls, unless there are clear allegations that families are acting outside the law.
Surely acting ultra vires should be outside the SS remit?
I don't know here whether SS are ultra vires. I expect so. In the woman's position, I would be writing a letter to SS asking at what age she is permitted to allow her son to walk to school alone, and asking them to quote the case law. And ditto, asking them at what age and for how long a period children may be a) in the house alone, or b) on some portion of the family premises alone and out of earshot. She won't get a reply. There is no case law, AFAIK.
In law, it is a parental judgement call, however much you or I might want our children to walk with us until the age of XX (insert suitable age here)