Weather-related claims cost British insurance companies an estimated pounds 1.3bn a year, and it has been estimated that some 30 per cent of those claims are - to some degree at least - fraudulent. One company, however, specialises in gathering the data needed to assess the validity of such claims.

"How many people do you know who live at the junction of two runways?" asks Stephen Roberts, and that question lies at the heart of the philosophy that led to the formation of his company, Weathernet. The idea came to him when he read an article about severe weather and the insurance industry. It told him that in an average year pounds 1.3bn was paid out on insurance claims, of which about 30 per cent were fraudulent or overstated. "I am no mathematician," he says, "but 30 per cent of pounds 1.3bn is lots, and I began to develop ideas of a service to help insurers better validate storm claims."

Now the Met Office has a huge network of stations spanning the UK, but since their primary interest is in prediction, they tend to report steady winds rather than sudden gusts, and they tend to be situated in places - such as the junction of two runways on an airfield - where there are no buildings nearby to distort the conditions.

So when a policy-holder tells his insurance company that a gust of wind blew his chimney down and it killed the cat, how are they to know whether it was the wind, or the stupid moggie, that pushed the rotting brickwork over?

That's where Weathernet comes in. The first stage for Stephen Roberts was to set up his own network of weather stations, independent of the Met Office, that reported maximum wind gusts. By the end of 1995, he had 50 such stations who could provide measurements of local weather conditions in urban areas. At that stage, the Weathernet project was taken on by the Cunningham Group loss adjusters. They have been providing a growing service to the insurance industry ever since, and, with 100 calls a day relating to real claims, are approaching their goal of being able to map weather down to the level of a postcode.

"The most interesting aspect is the observers themselves," says Roberts. "Some take their monitoring to extremes, and even get up in the middle of the night to take routine observations. This is fine, but can get a bit wearing when they ring you at 3am to tell you in excited tones that they have recorded 32.8mm of `moderate intermittent rain' in the last hour." Typically the observers are male (with one exception) and confirmed bachelors. One is so infatuated with the weather that he admits to suffering from an unseasonal form of Seasonal Affective Disorder: he gets depressed during hot summers because of the lack of weather to report. He would have loved to have been in Nottingham recently, when Weathernet's local man reported flying pigs as a tornado ripped through a pig farm. Any insurance companies facing claims from Nottingham for damage caused by flying pigs will be well advised to contact Weathernet for further information.

Cunningham Weathernet Ltd can be found at 4th Floor, Kingsland House, 21 Hinton Road, Bournemouth BH1 2DE (01202-296396).