IT’S difficult when your children first leave home and they’re no longer under your watchful eye.

Of course they’re adults and responsible for themselves. In many ways, it’s a relief.

What they do is up to them and there’s little point in you losing any sleep over it, especially when they’re living hundreds of miles away. But you worry about what they might be doing. You worry about what they might not be doing.

You just worry.

At least thanks to new technology – specifically the WhatsApp messaging service – I have a bit more of an idea of what my boys are up to than my parents ever did when I was in my 20s and occasionally called home from a payphone.

On our family group chat, the boys have shared photos and videos of everything from holidays to what they’re having for lunch, nights out, a sky dive and even a trip to a clinic to have a skin tag removed.

While I’m sure there’s lots I don’t know about, I do now get little glimpses into their everyday lives, even if I have to cover my eyes in mock horror from time to time.

One Saturday night I opened WhatsApp to discover a photo of our eldest lying on his sofa, dressed in pyjamas, playing a football game on the PlayStation. His girlfriend had added a caption revealing he had not moved from that position all day: “Oh my God, no!” I exclaimed.

Our 15-year-old took a look but couldn’t understand my concern: “What’s wrong with that?” he said, clearly longing for the day he could leave home and enjoy such perfect weekends himself.

Then last week, one of the boys sent us a worrying photograph of his brother being interviewed by a police officer, who was writing things down in a notebook, in the flat they share in London. Brothers do love to snitch on each other: “Patrick’s in deep trouble. It’s about last weekend,” said the caption.

We knew Patrick had been going out with a group of friends that weekend. But what could have happened?

The answer was not immediately forthcoming. “I’m sure he can’t have done anything wrong.

They’d have him down at the station for questioning otherwise, wouldn’t they?” I ventured to my husband. “I bet he’s lost his phone or wallet. It won’t be the first time.”

But then it dawned on us that police in London would hardly go out on a house visit every time someone reported a missing phone or wallet.

They wouldn’t have the manpower.

While we imagined all sorts of horrific scenarios, Patrick let us sweat for an hour. Eventually he told us: “I’m a prime witness. The girl in the flat below has a weird guy stalking her. Last night he was on my balcony at 3am.”

It turned out Patrick, who is about 6ft 5in and has a history of stepping in to help people out when they’re in trouble, has already intervened twice when the crazed stalker has appeared banging at the front door.

In an attempt to reason with him, he has tried to have sensible discussions about how he shouldn’t be in the building and has encouraged him to leave quietly. “So what did you do when you heard him out on your balcony, Patrick?” I asked. As I suspected, he leapt straight out onto the balcony.

Patrick has clearly watched too many films where the leading man or woman heads directly for the source of the noise in the night, when any normal person would run in the opposite direction. “You realise they only do that for dramatic effect, Patrick. It’s not the sensible thing to do,” I groaned.

But, he attempted to reassure me, he did grab the nearest thing to hand to use as a weapon in his defence, should things get out of hand.

So, what was the nearest thing, Patrick?

A cricket bat? A hammer? A heavy book by your bedside?

“Well, it was three in the morning, and I was a bit bleary-eyed and only half awake,” he explained, slightly embarrassed. “The first thing that came to hand was a coat hanger.”

And, no, not a wooden one, nor a metal one. It was a plastic coat hanger. Luckily, the stalker took one look at Patrick waving his brightlycoloured piece of plastic and fled.

“But what if he’d had a knife, Patrick? This sort of behaviour is irrational and illogical. And he may now see you as getting in the way of the object of his obsession.

These people can be so unpredictable.

“Please, please promise me you won’t engage with him if he appears again, that you’ll run out of the building and phone the police immediately.” He nodded his head, but I’m not so sure.

As I say, you worry. You just worry.