"I've lost my wife," he says into the receiver.
He's using a proper phone, a landline, which is one way to know you're at your parent's house. The other is when the two of us get on with eating our roasts while mum's out for a walk, and dad mentions a family friend leaving a message on the answering machine, and I get this flashback to a time when you'd come home and listen for the slow beep that told you someone had thought of you while you were out.
"...and I'm not being, you know, that sounds strange but she has dementia and she went out for a walk, and hasn't come back. It's unusuaI. I'm not sure where she is."
Then he describes what she's wearing, which is, as usual, her favourite colours all at once: red trousers, a red jumper, purple wellington boots, a green puffy jacket (zipped up) with a hood; an outfit we earlier assessed as being "a bit much" for a sunny almost-hot day, but as happy coincidences go, has ended up giving us quite the distinctive Missing Person look to work with, so there you have it, who's laughing now.
Well, not so much us, to be fair. Not that we hadn't tipped from slightly exasperated to amused eye-roll two hours earlier when we gave up trying to convince her to wear something else. Maybe... leave the winter jacket? Unzip it at least? No, you don't need wellie boots, it's not muddy, it's 23 degrees! And then a fairly standard comedy sketch ensued: me trying to hide the offending items in the garden - next to the recycling box this time - her finding them five minutes later, by which point we were a bit like, “oh go on then, ok, off you go” without checking anything else.
And now she’s left her phone on the side which means she can't call us to say “I’m lost”, and we also can't track her using Find My iPhone - the modern day, tried and tested method of locating errant teenagers and parents gone MIA - and the handbag containing cards with her name and dad's number is in the living room, where she, currently, is not.
In the dwindling warmth of an April bank holiday Monday we drive around our quiet area of north west London, peering down roads she’s got confused on once or twice before. I walk through our local park squinting sideways into the trees and across the grass, scanning groups on blankets, supressing a mild irritation at all the sunny day picnickers who piled up their rubbish next to the bins.
“Bloody mess people have made in there” I say, irrelevantly, when I get back to the car with a nope, no luck shake of the head. Back at the house dad says "bet she'll be there on the sofa with a cup of tea and a sandwich.” But no, of course, she’s not.
Within five minutes the voice on the end of the landline says they’ve found her, she's ok, she's fine; an ambulance picked her up and she's been taken to Northwick Park.
Before we leave for the hospital I walk through to the kitchen, where the full plate of roast dinner that served as a reminder of her absence sits, cooled to her preferred temperature on the table - that's how she likes food now, inexplicably cold - and I get a roll of paper towel and criss-cross two pieces over the top, so it's there ready, waiting, for when she gets back.
Read more thoughts from London here.