Military helicopters winched dozens of people to safety and emergency workers in bright orange inflatable boats rescued scores more after an unprecedented deluge.
British soldiers conducted house-to-house searches for those trapped by floods as deep as 8 feet (2.5 meters). Troops also dropped down on lines from Royal Air Force helicopters, breaking through rooftops to pluck people to safety.
Constable Bill Barker, 44, died as he joined rescue attempts, swept into the surging waters when a major bridge collapsed. Emergency services said more than 200 people were rescued in the hardest-hit town, Cockermouth and about 1,000 homes were flooded.
In a message to local officials, Queen Elizabeth II said she was "deeply concerned and saddened by the dreadful flooding across Britain." British Prime Minister Gordon Brown said Barker "was a very heroic, very brave man."
Britain's Met Office said a record 12.3 inches (314.4 millimeter) of rain fell in 24 hours in the area -- the heaviest rainfall ever recorded in the U.K.
Cockermouth, a market town 330 miles (530 kilometers) northwest of London, lies at the junction of the Cocker and Derwent rivers and is known as the birthplace of poet William Wordsworth. The flood was "of biblical proportions," local House of Commons lawmaker Tony Cunningham said.
Heavy rain and gales also brought widespread flooding to Ireland, as more than 3 feet (1 meter) of water shut down the center of the country's second-largest city, Cork, and more than a dozen towns and villages. The Irish army was used to rescue the stranded from waist-deep floodwaters and a helicopter winched to safety a County Galway family of five, including the 87-year-old grandmother.
Floods caused transport chaos along Ireland's western coast. At the Lake Hotel, on the shores of the fabled Killarney Lakes in County Kerry, about 170 guests at the Victorian period building were evacuated by tractor, as staff carried period furniture upstairs.
Irish weather forecasting service Met Eireann said parts of southern and western Ireland suffered their most intense and sustained rainfall in 30 years.