The Eighties were symbolised by Yuppies, the Nineties by new Labour - are the Noughties to be typified by the reluctant landlord? The rental market is being flooded with properties that their owners cannot sell - leading to the first fall in rents in five years, according to the Royal Institution of Chartered Surveyors (RICS).

Corroboration for this oversupply comes from the London estate agent Douglas & Gordon, which says that the number of rental properties has doubled since January, and from Savills. “We've seen a huge increase in rental properties where the owners cannot sell,” says Jane Ingram, national head of lettings at Savills.

The sheer quantity of “distressed rentals” has meant that rental prices have come down as tenants can pick and choose. The RICS figures show that 12 per cent more lettings agents said that rents had fallen rather than risen between August and October. That was a reversal from the previous three months, when nearly a third more agents said that rents were rising.

Susan Davidson is typical of the new breed of accidental landlord. “It's my worst nightmare,” she says. However, when her four-bedroom family home in Clapham, southwest London, failed to sell, the decision was made for her. She and her husband, Nick, and their two young daughters were well advanced in their plan to move back to Australia, so sitting out the downturn was not an option. “The idea was always to sell up here and use any profit towards a property in Sydney,” she says, “but the gamble hasn't paid off. I don't want the hassle of letting this place, but we can't offload it.”

The house next door to hers sold for £875,000 last year, but despite initially marketing her own home for £830,000 and then reducing it to £798,000 in June, a similar house on the street was put up for sale at only £695,000. Both houses remain unsold. Unwilling to drop the price farther, she felt that she had no choice but to become a landlord.

“I'd heard that lettings were booming because no one wanted to buy so I was looking forward to getting this really high rent,” she says. “We rang all the agents who told us that, yes, rentals were doing reasonably well - but not family houses.”

Susan has since rapidly gained knowledge of the market. “Our home, which should have been on at about £750 a week, was unlikely to make more than £650 - or £600 once the tenants had haggled.” Unable to sell her home or let it at the right price, she has decided to let the rooms separately, like Rigsby, above, in Rising Damp, with Nick retaining one for business trips.

Any accidental landlord would do well to heed the tax implications. Revenue & Customs has launched 7,371 informal investigations into buy-to-let landlords who may have underpaid tax in the past four months, according to UHY Hacker Young, the national accountancy group.

Fact file

Check that your mortgage lender will allow you to let your home - some will, but usually only for up to a year

If it is not permitted, a buy-to-let mortgage will often be at a higher rate than a residential mortgage and will be more expensive to set up. You will typically need 25 per cent equity in the property and the rent must cover mortgage interest by at least 130 per cent; you may incur early redemption charges by changing your mortgage

You must inform your insurer of a change of occupier and could find that your current policy is invalid

Maintenance and agency fees will eat into rental income (by about 25 per cent if the agency manages the property); any paper profit will be taxed

Should you let your family home for several years you may be liable to pay capital gains tax on any profit if it is eventually sold. However, it will remain CGT-free if it is let for less than three years

It is unwise to advertise your property for sale and to let simultaneously; tenants will be reluctant to take on a home that they fear will be sold at any moment

Be realistic about whether your property is likely to attract good tenants

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