o If all claims are residential: ?45 million to ?60 million ($75 million to $100 million)

o If 75 percent of the claims are residential and 25 percent commercial: ?80 million to ?105 million ($133 million to $174 million).

A loss of this value from flooding anywhere in the U.K. could be expected less than once every two years on average, according to the RMS U.K. Inland Flood Model.

The return period relates to the loss and does not mean this particular flood event is expected once every two years on average, the firm explained.

Claire Souch, vice president of product management at RMS, said, "The main determinant of loss will be the number of commercial properties affected, as commercial damage tends to be far more costly than residential and business interruption coverage can kick in."

She added, "At this stage, the ratio of residential to commercial buildings affected appears to be much lower than during the 2007 floods."

RMS noted that in June 2007 U.K. floods had caused losses of approximately ?1.25 billion to ?1.75 billion ($2.08 billion to $2.91 billion), while the July 2007 floods cost around an additional ?1 billion to ?1.5 billion ($1.66 billion to $2.49 billion if adjusted to 2008 values).

Instrat Guy Carpenter brokerage's U.K. unit said in an updated CAT-i report that around 1,300 properties are thought to have been affected by the heavy rain that triggered floods across northern England, southern Scotland and Wales.

In England, reports said, the towns of Cockermouth, Keswick, Workington, Burneside and Kendal in Cumbria County bore the brunt of the floods as rivers swelled.

The heavy rainfall also triggered flooding in Ireland last week, affecting western and southern regions of the country, including the city of Cork. Reports said the clean-up bill is expected to cost more than EUR100 million ($150 million).

The U.K. Environment Agency described the floods as a one-in-1,000-year event. At least 25 roads and 16 bridges in Cumbria were closed and several schools shut down. The Environment Agency said a month's rainfall fell in 24 hours in some regions.

In the Cumbrian town of Cockermouth alone, the EA said around 900 properties were affected after the Derwent and Cocker rivers burst their banks. The Environment Agency said the Floodline service received more than 17,000 calls from members of the public as the heavy rain fell last week. More than 1,000 homes were left without power and six bridges collapsed in Cumbria. All of Cumbria's 1,800 bridges are now undergoing inspections in the wake of the floods.