It was a rainy Saturday when I turned up at Battersea Dogs and Cats Home. In retrospect I was probably having a quarter-life crisis. I strode towards a startled receptionist, flung my palms on to the desk and said: “I’m ready for this.” My friend gave me a thumbs-up.

I’ve had Gus for a year now. In that time he has gone from a timid, slinking thing who wouldn’t be touched . . . to a furry lunatic. He chases his tail. He trashes my flat. He lies round my neck like a sassy fox stole. He returns proudly from the hunt with a carrot in his mouth. He’s emotionally needy, driving me to the point of exhaustion — and he has become my most treasured source of calm.

I wouldn’t say I got him on a whim exactly, but it all happened very quickly. No sooner had I told them that I’d never been to prison than a small woman in a fleece gilet was steering me to the cages.

She said she thought Dolly would be perfect — an elderly cat with just one tooth. The tooth would require brushing. I wasn’t sure I was up to the pressure of keeping the tooth in Dolly’s mouth.

In the cage next door was Gus, who had been bullied by his brother, Chunk. I remembered Chunk from the website, a magnificent beast with long, snowy-white fur, except for a perfect ginger tail that fanned out grandly beside him, his silky mane flowing in slow motion like in a Pantene advert.

This cage looked empty. “Gus is three years old. He doesn’t come out all that much but we’re sure he’s very sweet.”

I hunkered down, peered into the basket and met two panicked eyes. I murmured my very softest and most soothing: “Hey there, little fella.” He pressed himself against the back of the basket so hard that it fell over.

“I’ll take him,” I told the small woman. The others were trying too hard anyway.

I’d let myself into the flat and hear a violent crash as he shot from whichever flowers he had been chewing

Gus and I didn’t get on right away. For the first two weeks he spent 98 per cent of his time under the sofa. I’d let myself into the flat and hear a violent crash as he shot from whichever flowers he had been chewing back to his hiding place. I really thought I had made a mistake. I asked my friend how bad it would be if I took him back, like they do at nunneries with babies in baskets and a Post-it note. She said it would make me a terrible person.

One day I was sitting on the floor feeling a bit fragile and I got the sense I was being watched. I turned and saw a small head ducking and weaving behind the sofa arm. I froze. I tried to call him without moving my mouth. I felt like David Attenborough, urgently narrating a flighty gazelle.

I had been feeling very low that day. Overwhelmed. I’d been trying not to show it or to acknowledge it, but I had come home and shut the door and it was looming. I felt frightened. My body was falling into a heavier, hopeless thing; a warning sign. I hadn’t been depressed for a while, but I was tired and I felt lonely. I had broken up with a partner of three years and lost contact with many of our friends in the process. I was living by myself after she had moved out, with nobody to call, and I felt a sudden crushing sense of utter isolation. I felt destabilised. A faceless, general dread.

That tiny warm heartbeat lying on my right palm sent a wave of calm through my whole system

As numbness threatened to wash over, this small, strange cat came and sat on me for the first time. He kneaded my thigh as I sat cross-legged, willing myself not to breathe, and he curled up. That tiny warm heartbeat lying on my right palm sent a wave of calm through my whole system and took my babbling mind off the boil. We had ten minutes before I sneezed and he shot back under the sofa. From then on I realised bringing him home was one of the best things I’d done.

Nearly a year down the line, you honestly wouldn’t know it was the same cat. He has become an utter madman. I had assumed that all cats were stand-offish, aloof, proud, elegant creatures. He is none of those things. He is a needy, uncoordinated, boisterous lunatic; a freak among cats. He washes his face at the sink while I do mine; he uses his paw to guide my hand back to his head if I stop stroking him. Honestly.

When I come home, if he is in the garden, he will crash through the catflap to greet me like a labrador. I am fatigued by his cavernous need for love. I have heard a scrabbling at my window at 3am and opened the curtains to find him dangling the full length of the window pane from upstretched paws.

He makes me laugh at some point every day. I often sing to him; everything from love ballads to Nineties R&B. We breakfast together — which, in practice, is me eating on the sofa with an elbow stretched out to restrain him.

I sometimes wonder, as he lies on my chest, whether I will achieve a closer bond with another creature. I certainly don’t think any other person will feel such a need to be physically close to me. I have awoken to find his face millimetres from mine, one paw tenderly on my closed left eyelid, him gazing lovingly at the one I’ve been allowed to open.

I figure he is probably grateful I removed him from his bully of a brother; or the woman in the gilet who wanted me to take him for walks outside on a lead, rather than let him roam loose. He seems pretty happy these days, though. They say crazy people often are.

It’s much harder to feel deeply isolated when there is a small thing demanding attention

He has become an antidote. He makes me feel grounded and brings me a very simple, untouchable form of contentment. In the past I’ve found that bouts of bad mental health begin with one evening. A night when the clouds come down and I realise I just don’t care as much — about anything. Since I’ve had Gus, that feeling has crept over me several times, and each time he has chirruped, ambled over briskly and flopped down on my lap. A warm, vibrating, happy, silly thing — and it’s like armour. An invincibility. The power of the world to overwhelm is blunted and my dread dissipates.

It still shocks me how instant this effect is when I’ve found other things — such as medication — so fruitless. The weight of him keeps me in the room. Loneliness isn’t something I feel often, but when I do it can be really powerful. It’s much harder to feel deeply isolated when there is a small thing demanding attention.

I don’t tend to feel happiness in and for itself very often. It’s not a sad thing, it’s just how my brain is. I feel happy anticipation when I plan to see people I love; I feel satisfaction in completing things; I feel a happy sadness in nostalgia. Yet things that bring intrinsic contentment in the moment are very rare. I note them. Gus has without a doubt become one of the most consistent ones. He keeps my head in a safer place. Laying a hand on his white tummy as it rises and falls and feeling such uncomplicated love for that mad little beast makes me a better version of myself. And much happier.