It seemed like a good idea at the time. We desperately wanted to go on a summer holiday, but, having just bought an Edwardian terraced house in north London, lacked the wherewithal. As we brainstormed around the dining table one evening, my daughter hit on a solution — we’d rent out our spare room for six months to raise the money needed to go away.

“It’s a brilliant wheeze, mum,” Elen said. “The family of one of my friends is already doing it. When Jenni went to university, they sublet her bedroom; Jenni gets the rent from that to pay her tuition fees. It’s not dodgy at all.”

So started a long experiment in, as one of my posher friends sniffily called it, “living with lodgers”. Households struggling with the credit crunch might like to consider our experience. After all, the “rent a room” scheme is so smiled on by the government that you don’t have to declare rental income to the taxman — up to a ceiling of £4,250. If you’re a happy-go-lucky household, it can be a fun way of making a few extra pounds.

For us, the first step was to place a notice advertising “a large, airy room in a friendly family home” in Loot, the classified ads directory. I requested two written references and didn’t flinch from spelling out the drawbacks: no local Tube station; two teenagers, as well as a cat and a dog, already in occupation.

Within 24 hours, my phone started ringing off the hook, perhaps because I had kept the rent deliberately low, at £280 a month, all-inclusive, with one month’s rent payable as a deposit. After a week of fielding calls and interviewing wannabe lodgers — during which an assortment of students, waitresses and builders traipsed through our home — the room had a tenant.

Itsumi was an art student, who spent the odd Sunday giving my children free origami lessons. She liked our house because of “the carpet-free wooden floor, like my Japanese home”. We liked her: she was charming and quiet.

Two trouble-free years later — rent paid monthly like clockwork, never any arguments about sharing our tiny kitchen and bathroom — she left. Clearing out her room, we were astounded to find on the bookshelves dozens of glass jars containing spiders in various stages of decay. The collection, it turned out, had been part of a conceptual artwork for her final degree show. “Gross,” Elen groaned. “I’d have caught flies for them if she’d asked,” Shaz said sadly.

After Itsumi came Gloria, a Zimbabwean student nurse. She was a firm favourite with the children: kind and jolly, she regularly slipped them chocolate bars during the 18 months she spent in our house. The only mystery was her reluctance to utter the word “Mugabe” in anything above a whisper — “I have family back home,” she would say, before melting back to her room whenever the conversation turned to politics.

Then came our first slight hiccup. We took in Jean Paul, a courier by day and rock musician by night. His keenness to practise his electric guitar in the room elicited several tricky exchanges. Though charming and friendly in many ways, he stayed less than a year. We parted amicably, but the encounter convinced me that, although I’d told my mortgage and insurance companies I was letting a room, I ought to put the arrangement on a firmer legal footing. Until then, we hadn’t used a contract, merely agreeing that either side could give the other a month’s notice to quit.

Anna Favre, a solicitor at Pemberton Greenish, in London, was reassuring. “As long as a lodger is sharing a bathroom and kitchen with you in your home,” she advises, “they have no security of tenure.” In other words, there is no need to go to court to get an eviction order. Still, Favre advises drawing up a written agreement setting out terms. “Use ‘lodger’ or ‘licensee,” she says, “not ‘landlord’ or ‘tenant’.”

Reassured by her advice, we moved on to our next lodger. Kemal, a Turkish computer-studies student who’d come to London to brush up on his English, wowed my son, Shaz, with his footballing prowess every summer evening in the allotments. It was with real sadness that we said goodbye to him when he returned to Turkey. In comparison, his successor, Maria, a teaching assistant from Poland, seemed positively staid.

Our last lodger wasn’t really a lodger, but Elen’s schoolfriend Alisa, who needed a place to live after her father’s company relocated to Canada. After Alisa — who became like family, and whose contributions to the household are still missed, especially her Russian dinners of “ploff” (a spicy rice and lamb dish) — we stopped letting the room. As Elen says: “Nobody could live up to her.”

So how did it work, sharing with strangers? The answer is, surprisingly well. My children gained tolerance and a deeper understanding of foreign affairs. Every time I suggested ending the arrangement, they would argue for trying “just one more person”.

Elen, now 20, explains: “Many of our lodgers were crazy, like Jean Paul, but they were good to have around. It’s great to have had French, Japanese, Zimbabwean, Turkish and Russian people living with us. I always had mad stories to tell my friends at school.”

House rules? We started with none, but they evolved over time. The most important one involved the bathroom. With two teenagers heading for school each morning, I found the routine that worked best was to ask the lodger not to use the bathroom until after 8am. Before that time, we scrambled to get ready, bad-temperedly queuing up on the stairs. And anyone who used the kitchen had to wash their dishes after eating.

The most important rule of all, however, is this one — treat your lodger as a friend of the family, not a cash cow.

Shaz, now 18, recalls Kemal’s exploits with particular fondness. “Do you remember the time we all came down to breakfast and he had that blonde, leggy girlfriend there, wearing only one of his shirts?” he asks, eyes glazing over at the memory.

What you should know before taking in a lodger

You must tell your mortgage company and your insurance company that you are considering renting out a room in your home. Depending on the terms of your mortgage, you may need their permission.

Make sure you inform your local council, too, in case the addition of a person to your household changes your council-tax bill.

Vet people thoroughly. Ask for at least two written references, ideally one from an employer and the other from the previous landlord. Phone both and quiz them at length.

Take a deposit of one month’s rent, to be kept against breakages. We kept ours only once, when a mattress was ruined by being soaked with blood (don’t ask).

n Draw up a written agreement, including the notice period. Avoid terms such as “tenant” and “landlord”; instead, use “lodger” or “licensee”. Include as many house rules as you want and, if necessary, an inventory. If you are worried, run the agreement past a solicitor before accepting a lodger.

Specify which services you are offering in the room — a telephone line, WiFi, satellite television — and who is responsible for the bills.

Trust your instincts. If you don’t think you’ll get along with someone, don’t let them in.

Make sure you have a gas safety certificate, and that your furnishings comply with all modern safety requirements.

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