Read the fine print, then read it again

Many buyers contend that it would be easier to purchase a country mansion set in rolling parkland with a home farm, fishing rights and staff cottages than to buy a leasehold flat. No one should tackle the pitfalls of leasehold property combined with the perils of shared living under the same roof without doing their homework.

The biggest stumbling-block is, invariably, the lease. Always go through this minutely before committing yourself. The lease, of course, sets out everything you can and cannot do in your own home - from subletting, to how often you have to clean your windows. Check that your share of the service charge bill is fair. Look at the ground rent provisions. They may go sky high if they are subject to regular review.

"Leases are weird and wonderful things and they depend on where you are," says Howard Elston, of Strutt & Parker. "Get a local specialist conveyancing solicitor to go through a copy of the lease. He knows the quirks and can be more relaxed about them. For instance, the leases for several estates in South Kensington say that residents aren't allowed to keep pets but, in fact, the landlords turn a blind eye."

If you need a mortgage, lenders will generally ask for the lease to run for at least 30 years after the loan has been repaid. But lease length is not as crucial as it used to be. The 1993 Leasehold Act gave most tenants the right to buy lease extensions of up to 90 years. If the years left do not look good, try to get the seller to take up his option to extend before you buy.

When Mark Davies, a banker, offered pounds 129,000 through Foxtons for the 51-year lease on his large studio flat in South Kensington, it was in the mistaken belief that the vendor had already negotiated a 54-year extension. "When we discovered what had happened, the price fell by pounds 15,000, the sum the lease extension will cost me."

In many buildings, leaseholders have formed their own company to buy the freehold. "This means you have more control over your own destiny and the building should be cheaper to run," says Joshua Grinling, of Winkworth.

But paying too little can be dangerous. "Sellers often say to me that they are paying only pounds 200 a year in service charges," says Peter Rollings, of Foxtons. "That would frighten the life out of me. On flats priced between pounds 150,000 and pounds 250,000 I'd prefer to see charges of about pounds 1,000 a year. That allows for a sinking fund and shows that someone is thinking about the future. Charges that seem high but include heating and hot water could be good value."

Obviously, a well-maintained block keeps its value better than a neglected one. "Well-kept common parts can add 5 to 10 per cent to a flat's value," Peter Rollings continues. It is also less likely you will face unexpectedly large bills.

Joshua Grinling, meanwhile, advises buyers to "look at the common parts: has the exterior been repointed or repainted recently? Look at the level of porterage. Some blocks are overmanned."

When it comes to choosing between a purpose-built flat or a conversion , it's purely a matter of personal taste, says Joshua Grinling. "Younger people are more comfortable with a conversion because they know how much a new roof, for example, will cost. And if the freehold is shared between five units, and you have regular meetings, expenditure is more controllable". Conversions often have original features and more character, but rooms may have been awkwardly divided to create bathrooms and kitchens.

"With purpose-built blocks you have solid floors and good sound insulation, and the ceilings won't reduce as you go higher up," says Peter Rollings.

Older blocks need more upkeep, says Tony Halstead, a property consultant. "You may have to pay for a new roof, scaffolding, lift insurance or a new lift." And individual flat owners will have less say in how a large block is run.

Think about light, noise and security as well as resale potential when deciding which floor to live on. A top-floor flat may have wonderful views, but without a lift it could be hard to sell.

"The amount of light is very important to me," says Mark Davies, who, nonetheless, chose a basement flat. "My flat has french doors opening on to a patio; it doesn't look out on to the street, so you are not always looking at people's ankles; and, most important, the living-room roof is all frosted glass."

In theory, a flat offers the double security of the main front door and the flat's front door, but basement and ground-floor flats are vulnerable. Check how security-conscious the neighbours are.

Yet, as Joshua Grinling says, "If you really want to be in charge of your destiny, buy a freehold house."