I've placed my cat under house arrest - how unpleasant can that really be?

Geno, my 10-year old tomcat, has been placed under house arrest. Oscar Whisker-ius, I've taken to calling him. This is the type of joke which occurs to a person at 4am as they crouch, fuzzy-eyed, over a demented cat who has been singing a loud, mournful protest song for 36 hours. It's not a funny joke, but it's the sort of joke that might stop a person strangling a cat.

I will never actually strangle this cat. I love this cat more than almost all of the planet's human beings. Geno is a clingy, talkative, decidedly fey homebody who has spent a decade under a duvet, sitting behind my knees as I type. Imagine a slightly depressed Charles Hawtrey wearing a fur coat, if Hawtrey had a nigh-constant list of grievances over matters like the scant household supply of tinned tuna. That's Geno.

But now Geno is growing old and has started forgetting to come home for days at a time. Or losing track of where he lives, preferring to sit in next door's garden making a noise like an Adele B-side. It is, I will freely admit, breaking my bloody heart. Following his latest vanishing act – during which I didn't eat for two days, instead standing in the garden shaking a bag of Iams and chain-smoking Marlboro Lites – his open-door policy has been suspended. "For you, Geno," I said, as he appeared sheepishly on the patio on day three, "ze war is over".

At this point, it felt like I was being kind rather than cruel. Because how unpleasant can house arrest really be? I've always quite fancied it myself. Two or three years would do me just beautifully. I would not be remotely bored. I'd sleep a lot. I'd re-watch Six Feet Under from the beginning, and I'd nail how to make a perfect upright haddock soufflé. I'd finish What a Carve Up! by Jonathan Coe – which I've started 11 times since 1994. I'd learn conversational Spanish. I'd meditate to Tara Brach podcasts until I was so Zen-like I was punch-worthy. I'd get to grips with Kate Bush's Lionheart, and I would listen to Bitches Brew by Miles Davis every single day until I could think of one nice thing to say about it.

Obviously I'd also write my own Pulitzer-worthy novel, full of incredibly deep thoughts on my painful incarceration. But in reality it would not be remotely painful because I'd be leafing through Nigel Slater cookbooks and putting eBay bids on obscure Sophia Loren memorabilia and having long, waspy WhatsApp chats with pithy homosexuals which would give me all the fun of socialising without the hard slog of applying under-eye corrector and leaving the house.

At this point, someone always says – tilting their head as if humouring a berk – "Oh but Grace, would you not miss people?" And I would, a little bit. But the thought of having no choice but to submit to life as a pampered hermit overrides that. "I would love to come to your house for 'nibbles and a catch-up' – which we both know is a veiled plot for me to donate to your organic porridge Kickstarter fund – but unfortunately the Government will not allow it. I know! I'm all the sads too!"

These are also the sort of things I think at 4am as the now imprisoned Geno makes his umbrage obvious. This is a cat who has never been overly fussed about the outside world. A typical feline life of rough-and-tumble has never been his thing. The only mouse Geno has ever brought home was in such a state of decay that it had clearly been killed weeks previously by another cat.

During long cold winters Geno's unwillingness to exit the house and expose his delicate arse to frost has led to me providing him with a hooded litter tray. Oh the smells. The horrific nocturnal scratching of litter. The manner in which he hovers patiently as I dispense with his past ablutions and replenish the tray with fresh litter. And then he runs in to begin straining again.

And now, after all this, Geno wants to be feral. The vet has checked him for all manner of illnesses. See my credit-card statement for details. Geno's renal facilities are functioning. There are no skin lumps or bumps to fret about. His thyroid is tip-top. His paws and his claws are perfect. He has no other signs of senility aside from his determination to live as a tramp.

"Is there a chance," I finally asked, on the third visit, "that there is nothing at all wrong with this cat and he has simply decided to be, well, a bit of a dickhead?" The vet answered, "Um, well, yes. He may just stop doing it. Try not to worry. But in the meantime – including the scans – that'll be £127."

Geno's time in cat Colditz continues. There are two of us in this prison.

@gracedent