E Jane Dickson: Con wants the face cream for his spy-work. 'It makes you 10 years younger, so if I put it on, I'll disappear'

Rows and rows of furry toys are laid out on the hall floor, like the aftermath of some grand Edwardian shooting party. Now that she has her own bedroom, Clara has decided it is time to put away childish things. Stalking up and down the lines, she reviews cuddly mice, bears, kangaroos and pandas with an implacable eye. The most highly favoured are set aside, while the rest are shovelled unceremoniously into black plastic bags for the charity shop.

Rows and rows of furry toys are laid out on the hall floor, like the aftermath of some grand Edwardian shooting party. Now that she has her own bedroom, Clara has decided it is time to put away childish things. Stalking up and down the lines, she reviews cuddly mice, bears, kangaroos and pandas with an implacable eye. The most highly favoured are set aside, while the rest are shovelled unceremoniously into black plastic bags for the charity shop.

Three weeks ago, such a cull would have been unthinkable, but since Grandpa has finished his grand projet - an arrangement of partition walls and skylights that magics up an extra bedroom in the limited square footage of our flat - we have become intensely aware of personal space. Clara is fussy about whom she allows into her boudoir - a pink and white chamber worthy of the infant Marie-Antoinette. Visitors granted a viewing are directed to the armchair, while Clara receives them from the gauzy belvedere of her bed.

The entrance to Con's frog-green room is criss-crossed with trip-wires, sensors and electronic listening devices. Ideally, he would have liked a piranha-filled moat, like Blofeld's in You Only Live Twice, but there's a limit to what you can do with MDF and Ikea flatpacks. Hi-tech security notwithstanding, you must also give a password; not a pre-arranged password - this makes things too easy - but a password you have to guess. The entry process can therefore be quite lengthy.

"So, Mummy," says Conor, when I finally crack the door-code ("James Bond" is the key phrase du jour), "I have been expecting you." It turns out that he has been meaning to speak to me about my appearance. "Have you heard, Mum," he begins in a tactful, conversational way, "there's stuff you can put on your face that makes you 10 years younger? I saw it. It was on TV."

"Wow!" I reply. "Put me down for a caseload." Clearly, if I'm not to suffer the same fate as Clara's furries, I'll have to smarten myself up for life in the designer zone.

"And when you get it," Con continues, "can I try some?"

"What on earth do you want with face cream?" I ask, surprised at this new interest in personal grooming.

"He thinks it will make him invisible," explains Clara, who has arrived, with much bleeping, in Con's den. She is carrying a cradle-load of dolls which she doesn't want cluttering up her room, but which she generously thought her brother might like.

Con nods and quickly cases the joint before speaking. "It's for my spy-work," he whispers. "The cream makes you 10 years younger, and I'm only six, so if I put it on I'll disappear!"

"I'm afraid it doesn't work quite like that." I tell him. "If it did, I'd buy three jars and be skipping around like a teenager. " Conor looks crestfallen. "And anyway," I say, pulling him to me, "I don't want my boy to disappear."

"And we don't wan't you to look like a teenager." Clara tells me, nudging her brother in the ribs."

"God no!" says Con. "We love you looking old."

"Well then," I say, pulling my ancient features into a withered grin, "we're all happy." And I try, really quite hard, to be flattered.