Like all our neighbours, she wouldn't think twice about helping other folks' kids, or giving them a clip round the ear when it was merited.
And if your father heard you'd been cheeky, an ear would not be the only thing stinging.
Yes, innocent days, when parents were free to use their own judgment and experience to decide who their children should trust.
Today, we are required first to subject every Mrs Petrie to government scrutiny.
We've reached the sorry state where some parent's stinging rebuke would be the least of your worries if you merely looked the wrong way at their little darlings.
You could expect social services to knock on your door or, worse, an invitation to help Police Scotland with their inquiries - and an end to normal life as you know it.
Channel 5 last week reported on a social experiment to test the caring British public.
Sisters seven-year-old Uma and five-year-old Maya Rumsey took turns at looking lost one Saturday in a London shopping centre.
In one hour, 616 passers-by ignored them. Only one stopped, 70-year-old granny Pearl Pitcher.
People gave a variety of reasons for not stopping, saying it was an obvious stunt, with the film crew nearby, or that the girls showed no real distress and stayed silent.
Other embarrassed pleas in mitigation blamed London pickpocketing gangs - many of them foreign - which use children, Fagin-like, to lure marks.
We even had the NSPCC suggesting the lack of Good Samaritans was due to people being too busy.
Sorry, that's apologist tosh, unless by too busy they mean pedestrians with headphones or a mobile glued to their ears, so engrossed in their own wee world they wouldn't see a bairn - or a bus - unless they tripped over one.
Too busy? No, the recurring reason given for walking on by was fear, and the certain knowledge that any concern could be misinterpreted.
The girls' mother, 39-year-old journalist Reshma Rumsey, said she was "gobsmacked" so many people made a conscious effort to avoid helping her children.
I'm gobsmacked she's gobsmacked.
The NSPCC in response declared that a child's welfare is more important than worrying about being labelled a "stranger danger".
Their spokesman said: "We have to get a message to adults that they have a responsibility to protect children and that must supersede any concern you have for other people's perception of why you are reaching out to help that child."
Responsibility, that's spot on, but the rest is more tosh.
There's no "perception" about it, it's reality that adults today fear being labelled a paedophile if they interact with a child.
And who instigated this "stranger danger" hysteria, this culture of suspici on, if not the children's charities, those self-styled extensions of the nanny state, egged on by sundry do-gooding, self-serving child advocates and whipped up I have to say by the media's own paedophile paranoia.
Successive governments have pandered to politically correct madness and created a child abuse industry. Good Samaritans have been conditioned, bludgeoned even, into suppressing their natural compassion.
As child protection measures have escalated, every volunteer - the one-time pillars of every community - from Mrs Petries to youth leaders to sports coaches to Santas, have been made to look like potential child abusers, deemed unsuitable to have any contact with children until Disclosure Scotland has checked their cupboards for skeletons.
EXTRACURRICULAR activity has collapsed. And what's the legacy? Fat kids and frightened adults.
Vetting is fine, but it's not fail-safe. It can check only previous offences, it's no guarantee someone will behave in the future.
Would vetting have exposed Jimmy Savile, or abusive priests and children's home staff, perverted celebrities and grooming gangs?
Obviously we need to identify such risks, but over-zealous regulations have deterred volunteers and eroded trust.
They may even have done more harm than good, in giving children a malign power over adults.
You can't even take pictures of your own child, for goodness sake, and we've heard of primary school teachers being told never to give an upset child a cuddle.
One parent, fearing the worst when summoned to her child's nursery school because "she'd had an accident", found the wee lassie distraught because she'd wet herself.
Spare pants were still in the tot's bag, because the staff refused to change them.
I'd like to believe that kids looking lost in the St Enoch Centre or Buchanan Galleries would provoke a more human Weegie response, but you'll be damned if you do, and damned if you don't.