Don't forget your postcode: it does make a difference

The website that tells you what your home is really worth has gone nationwide ­ estate agents everywhere may find honesty the only policy

Hometrack.co.uk is an online independent residential property index, a guide to prices and trends by area. The service had been restricted to Greater London with information "from more than 700 of the best agents within the M25", but as of this month there is comprehensive data on properties across England and Wales.

Hometrack.co.uk is an online independent residential property index, a guide to prices and trends by area. The service had been restricted to Greater London with information "from more than 700 of the best agents within the M25", but as of this month there is comprehensive data on properties across England and Wales.

The site gives a monthly picture of performance for properties, using comparisons based on transactions agreed in the previous month. December 2000's figures show that W8, Kensington, was indeed Greater London's most expensive area, at £1,185,417 for an average terraced property.

But before turning up your nose at SM6, Wallington, bear in mind that this area showed the best performance for terraced properties, with an increase of 4 per cent compared with under-performing postcodes such as N15, South Tottenham, N16, Stoke Newington, and WD7, Radlett, who all reported a 4 per cent decrease in price.

Critics may say information on "hotspots" is meaningless unless you track a particular area over a longer period. For example, December's hotspots were shown as NW2, NW11, EC3, EN5 and E14. By February none of these areas features again and RM10, Dagenham, with an average change of 6.33 per cent, tops the list.

Giles Mackay, who founded the site with Patrick Currie agrees that a longer-term view is needed but only in relation to hotspots. "Clearly hotspots are things people want to know about and they will soon be able to look at how areas have performed quarterly and annually. If you take a three-month trend you get a better picture."

The site is constantly improving its information which it began collecting on the Greater London area eight months ago. In four months visitors will be able to access the full annual picture. Mr Mackay says: "Our data is used by the Council of Mortgage Lenders and the Bank of England, and a new cut of data is now going on to many property websites. People can enter their type of property and postcode and find out how much the price rose or fell that month."

The Halifax and Nationwide produce figures based on completed mortgages ­ but how does this compare with hometrack.co.uk's information? One way of measuring is to compare against data produced by the Land Registry, who estimated the average price of a detached house in Greater London at £440,962 in December, the most recent available. Halifax reckons £374,465, compared with £270,319 from Nationwide. Hometrack.co.uk put the average at £419,764, which pleases Mr Mackay. "We're checking our data against that produced by the Land Registry, and it's very close. We're happy about the probity of data."

Postcode-junkies are in the right place for a heavy fix of information, but its relevance is more pertinent to buyers and vendors. Drilling into last month's figures for Dagenham reveals an average sale price of £90,000, with 98 per cent of properties achieving their asking price after an average of six viewings, and a 10 per cent rise in new buyers registering.

Buyers and sellers in hotspot number two, London SW7, with an average percentage increase of 6.25 per cent, may be interested to know that the overall average sales price is £690,000, with 97 per cent of properties selling at asking price after an average of 24 viewings and a 3 per cent change in new buyers registering. This should give ammunition to sellers who suspect their chosen agent is under- performing. A seller in Dagenham may be concerned if their sale is taking significantly longer than the six-week average recorded for February.

Patrick Currie hopes that giving consumers access to information normally reserved for professionals may tempt them to try out hometrack's sales service, launched this month. "When owners decide to sell they contact various agents, get valuations and often take the highest figure. How do they know if they have found the agent who will be the most effective at tracking buyers?"

A sellers' move-manager allows vendors to input their property details and postcode. Two local agents will filter the information through a 100-question survey and produce a report on your property's five strongest and weakest points, valuations backed up by comparable recent sales, a saleability rating and their charges, which may be discounted. If you can stomach your home's five weakest points, or cannot tolerate your agent's excuses, it may be a service worth trying.

¿ hometrack.co.uk