In London, they say, you are never more than 10ft from a rat. But, despite having lived in the capital for almost 30 years, I had never seen one. Then, one night recently, my wife, Jo, and I were having supper in our little one-bedroom flat in Camden when I saw something dark moving across the corner of the room. “What’s that?” I asked, my mind only half on it.

“Oh, my god!” said Jo, jumping to her feet. “It’s a rat.”

It was. Black, half the size of a cat, definitely not a mouse. Our plates were abandoned and we rushed into action – at least, Jo did. While I cowered in the background, she grabbed the metal-tubed brush from our vacuum cleaner. The rat had shot off into the bathroom. Neither of us was keen to follow. Aren’t rats at their most dangerous when cornered? And haven’t they been known to jump at men’s throats?

A short altercation later, we tiptoed into the bathroom together. The rat had vanished. Escaped, or maybe gone to ground in the murky space behind the bath panel. I closed the long decorative oval that curves above the floor with gaffer tape and cardboard. We barricaded ourselves into the bedroom and slept dreadfully.

My brush with disaster

Traps, poison and pest control couldn’t do it. So how did our correspondent get rid of his dirty rat?

Next morning, we loaded up with poison at the hardware shop. We laid it in shallow containers, then left for the weekend, praying that this had been a one-off. In a country hardware shop, I spent £20 on four Ultrasonic Rat Repellers. They plug into mains sockets and, the packaging promised, produce a high-pitched screech that drives away any rat within 100yd.

We returned on Sunday night hoping for the best. We found the worst. Ratty had been been back, and he’d brought some friends along. There were dark droppings everywhere: on the lovely orange carpet I’d bought in Marrakesh; even on our stainless-steel work surfaces.

A bottle of olive oil had been knocked over; the plastic at its neck was chewed horribly. The rubber flanges of the waste disposal had been munched to nothing, exposing the metal within. The rats had urinated everywhere. One poison tray had been knocked over; the others were untouched.

We took a deep breath and started to clean up. I plugged in the ultrasonic devices. Out came the gaffer tape again, this time for the holes in the floorboards and skirting.

Jo thought one of the invaders might be hiding under a stash of paper under the chaise longue. As she tugged the paper, a 9in rat jumped out, its long, rubbery tail passing within an inch of Jo’s bare arm. It shot into the bathroom and vanished.

Shaking like leaves, we covered every hole and laid more poison. In holes, down the stairs, in the dark, dingy well behind the basement storeroom, owned by a shop, which I believed to be the source of our problem.

We barricaded ourselves. Silence. Then, just after midnight, a sound of scratching under the floorboards announced Ratty’s return. Had he been deterred by our trusty ultrasonic device? Apparently not. He surely couldn’t get out, but maybe I’d missed a hole. I didn’t sleep well.

The next day, Monday, I called Camden council. Its website boasted a 24-hour response time for indoor rats. They couldn’t come before Wednesday – and each night the rats were back.

I’d been pinning my hopes on the man from the council. A rodent expert, he would surely find the nest (if nest there was) and sort out our problem. Not a bit of it. He was reluctant even to look in the basement. He hadn’t brought his own ladder, and couldn’t go down ours because of health and safety. “All I can do is put poison down,” he said. “You’d be better off doing it yourself – save yourself £67.”

I coaxed him down the ladder. There were droppings everywhere, but our man couldn’t get through to check the sewer hatch or the interceptor cap that prevents rats entering the drains. There was too much junk. If we cleared up, he said, he might have a look. He left bags of poison, filled in a form and said he’d be back in a fortnight.

For a few blissful hours that night, I thought the poison had worked. Come midnight, however, the scratch-scratch was back. Only this time it was more a crazed gnawing, as Rat One, Rat Two – even, who knows, Rat Three – savaged the copper pipes by my boiler. I lay there fretting, then got up and banged on the floor with a shoe. Hard. About 50 times. Amazingly, this did the trick. Ratty had departed.

The next day, my freeholder finally arrived with her builder, Gary. He was more fearless than the man from the council. In the basement, he found a broken drain cover and a smashed toilet. If the rats had moved from the sewer into the drains, this was their way out. A climb up the drainpipe to that hole under my bathroom wouldn’t be a problem. He got to work.

I bought two fearsome Lucifer traps and, following a tip from a rat-expert friend, baited them with Mars bars covered in peanut butter. I then ventured nervously into the basement.

Who should be waiting round the corner in the sunlight but Ratty? He didn’t look well. Watching him stagger about blearily, I almost felt sorry for him. But not that sorry.

The traps stayed untouched. The combination of Gary’s mending and the poison worked. Whatever rats were on the loose were poisoned; the others were trapped in the drain.

A week later, I persuaded Camden pest control to return. It gets about 500 call-outs for rats a year, and about 1,000 for mice. This time, the guy was a bit more switched on. At the front of the basement, under the road, we found the sewer hatch and opened it. Lo and behold, no interceptor cap. The rats would have made it up the drain, through the smashed toilet and up into the flat.

We had learnt our lesson. To get inside, Ratty had broken through four lines of defence: interceptor cap, broken drain, hole in bathroom exterior, then holes in floor and skirting. From now on, in any place I live, I’ll make damn sure they’re all firmly blocked.

Rat tales

- There are more than 60m rats in the UK. One in 20 properties in the country is infested with them, according to the 1995 National Rodent Census.

- More than 4,000 rats are born every hour in London. The brown rat (Rattus norvegicus) is flourishing in our cities, feeding on fast-food leftovers. Its relative, the black rat (Rattus rattus), helped to spread bubonic plague in London in 1665.

- Rat urine carries a water-borne bacteria, Leptospira, which can cause Weil’s disease in humans. Early flu-like symptoms can be followed by liver or kidney failure, even death.

- Rats’ teeth are coated with an enamel stronger than industrial diamonds, enabling them to chew through metal or masonry.

Explore Property

• Buying & Selling

• New Homes

• Overseas

• Interiors

• Investment

• Gardens

• Cool In Your Code

• Specials

• First-time buyer

Times recommends

• Second homes: credit crunch casualty or money-spinner?
• How I built my own sliding house
• Top 10 incentives for house buyers