Small, Medium and Large pose no threat to anyone’s national security but their sudden movements, mysterious disappearances and habit of carrying potential weapons in their rucksacks keep bringing them – and me – to the attention of the authorities.

Last night we returned home to France (first time I have ever been able to say that) from a brilliant eight-day trip to London feeling utterly exhausted.

Getting on and off the tube, weaving through peak-hour pedestrian traffic and general sightseeing with three boys required a level of vigilance that was testing for a woman who embraces the “loving neglect” approach to parenting. Not being entirely sure where your children are every minute of the day is not really a problem in a leafy suburb in Auckland or a farmlet in Provence. It’s different in the heart of London.

“Where’s Medium?”

“I thought Large was with you!”

“I’ve lost Small.”

A shiny stone, a piece of chewing gum art, a distant busker – anything could make any one of them lurch swiftly and silently out of sight.

Asking for help is the last thing you want to do because there is no “I’m-sure-he’s-close-by-but-I’m-getting-a-bit-worried” category of missing.

Staff at a crowded Westminster Abbey or Hamley’s Toy Shop need facts. Is the child missing or is he not missing?

The child is missing.

Then it’s real and you are instantly terrified and the drive to search becomes desperate – but you have to stop searching because the person you are speaking to wants you to accompany her into a very, very slow lift and down many, many floors to a security department where a person with very, very slow handwriting wants to write down Small’s full name and his age, and physical description and extensive details about his clothing and where he was last seen and he can’t understand your accent so you have to repeat everything four times and all the time no one is looking for the missing child because his father has been told to stay put with the other two children.

Then you remember: the meeting place. Ridiculous to imagine your six year old could find his way there through several levels of the world’s biggest toy store but the staff member begrudgingly agrees to break protocol and accompanies you to check– and there he is. A wee blond dot all alone in London watching a neon canvas demonstration while he waits for his parents to show up.

“It’s him.”

Now it’s time for the moment of judgement. It might be a small, tight smile. Or a warning.

“This is a nice place but not everyone who comes here is nice,” a man in a robe told me, moments after we were reunited with Medium in Westminster Abbey.

“Your succour sucks,” I didn’t say.

“Can you guarantee me that you will not let this child out of your sight again if I let you back in?” said the man in uniform on the HMS Belfast, who, it transpired, had pounced on Large and marched him to the entrance to page his parents despite the fact that he was neither lost to us or himself but was simply exploring independently, as 11-going-on-12 -year-olds do.

“We didn’t lose him on purpose,” I told him, slightly taken aback that he was giving me a dressing down rather than cheerfully reuniting me with my “lost” child.

Fair to say, by the time we arrived at Gatwick Airport, we were relieved at having maintained the head count we had started with. And the kids were sick to death of being in places where you cannot run or jump or playfight or shout or make sudden movements or flop onto the ground or disappear.

Within minutes of arriving at border security we were separated again when Small was taken aside for an explosives check and physical search. I assumed it was random until we were taken aside by another officer who held up Small’s ruck-sack.

I watched in horror as the officer reached inside and pulled out a bomb – well, a bottle of water, but we all know why they don’t let those through security checks.

The officer gave us a hard look, carried out a half-hearted interrogation then held up the bottle, and pronounced sentence: “You can’t take this with you.”

That was a relief. Off we tried to skulk, but no. Now Medium’s bag was being held up by yet another officer. This one was better at assessing the difference between cock-up and conspiracy and smiled at Medium.

“Don’t worry love, it will be fine. Let’s take a look shall we?”

She unzipped the bag and began pulling out potential terror threats:

• 1 Ee-ow the cat
• 1 Packet of felt tips
• 1 Westminster Abbey brochure
• 1 Science Museum handbook
• 1 Paper plane
• 1 Torch

“Ah,” she pronounced, reaching into the crumbly, sticky depths of his bag to pull out a tiny pocket knife. “This will be it. Right at the bottom.”

“Oh no,” I said. “I’m so sorry.”

Somewhere in the back of my mind a memory was holding up its hand and jiggling in its seat. Something about me putting that pocketknife in his bag a few days earlier. I ignored it.

“I’m terribly sorry,” she said to Medium. “But you can’t take this with you. It’s too sharp.”

Medium’s eyes widened in an: “I’m going to be brave,” expression that makes my heart break every time. He nodded.

Free at last, we stumbled toward Duty Free, where Sabbatical Man had an epiphany.

“I think we should check the kids’ bags before we fly next time.”

That’s the sort of thinking that got him where he is today.

An hour later in the boarding queue, almost home free, I heard someone hissing at us from knee-level.

“Will you keep your children under control!” a woman sitting on her backside was raging. “I have a very bad shoulder and I’ve already almost been knocked by one of the little beasts running around!”

She went on, using her good shoulder to shrug off my bewildered apologies and attempt to help her to her feet. It had been a genuine accident. She had knelt down, Large had turned and seen the space in the queue, but not the person at the bottom of it, and had walked right into her. He had immediately apologised.

There were plenty of times on this trip when our kids were naughty – but not this time and I could feel eight days of tension building into a bullet of rage aimed at the back of that woman’s head.

So you may now present me with my Award for Outstanding Modelling as a Parent because instead of firing, I told my children that it is very hard for people who live with pain and instead of  getting upset, we should feel sorry for her.

London is a great place, a fabulous destination and we really enjoyed so many things – but it is not easy with three boys.

It was such a relief to wake up in Provence this morning surrounded by grass and garden and trees, to let the boys sleep in and then let them run wild – scorching moss with a magnifying glass, making a train out of boxes, playing spies, searching for wild asparagus amongst the thistles. For most of the day they were out of sight and out of control – and it was a good day for everyone.