Alice Wylie: Does your mother know?

Ah, but you don't know about the Bad Thing she once did," says my Naughty Little Sister with a sly grin when I tell her that she's overreacting to my mother's daily phone calls to check up on her.

It's just what mothers do, I try to explain. She calls you every day. You ignore 50 per cent of the calls. She sends you thrice-daily text messages about the Christmas lights, the royal wedding, her new fitness regime which involves jogging on the spot for 30 seconds a day. You humour her. Everyone's happy.

Then Naughty Little Sister tells me about the Bad Thing. Last year I went away with friends for a long weekend in some far-flung cottage up north. I forgot to tell my mother. I had no mobile phone reception.

Mother grew irate when she received no response to her voicemail asking how to update her Facebook status. She grew positively frantic when she received no response to her text message asking me if I thought a novelty draught excluder might make a good birthday present for my father.

And so, 78 unanswered calls later, she reached for the spare key to my flat, the one I gave her "for emergencies" and decided on an impromptu "visit" to check I'd not fallen foul of one of my precarious towers of books she's always warning me about. She found nothing. I found a spot of mobile phone reception, got in touch and was none-the-wiser about her little road trip. Until Naughty Little Sister, who had been sworn to secrecy, spilled the beans.

I was actually rather amused by her actions, and to her surprise considered them justified. She was, of course, unrepentant when confronted, observing only that my flat was rather untidy and that she felt she had showed remarkable restraint by not going through my cupboards.

Anyway, I do acknowledge that it was all my own fault. I didn't tell her where I was going. I gave her a key. Did I mention I didn't tell her where I was going? I am fully aware of both her flagrant disregard for boundaries and her constant (and not entirely unfounded) concern that my carelessness will be my undoing (this is a woman who suggests I adopt what she calls "the brace position" when waiting at busy traffic lights, a sort of sturdy stance to prevent other pedestrians jostling you into the traffic.)

And, most importantly, I didn't tell her where I was going. That evening I happened to see 127 Hours at the cinema, the true story of a hiker forced to amputate his own arm with a blunt penknife after it became trapped under a rock. He knew that no rescue was on its way because he hadn't told anyone where he was going, including his own mother, whose calls he had ignored the morning he set out, no doubt in an attempt to avoid being quizzed on the subject of novelty draught excluders.

Suddenly I have panicky visions of becoming trapped alone and unnoticed under some fallen rail of clothes in Topshop, rescued by my interfering mother just as I'm poised to amputate a limb with a nail file. As James Franco is sawing through some particularly sinewy bit of arm on screen, I text her from my cinema seat to assure her that, from this day forward, I will always tell her where I'm going. Her response is immediate and triumphant: "Enlightenment at last."

• This article was first published in the Scotland on Sunday on January 16, 2011