Around 80,000 households remain without electricity, with Wales the worst affected by the "Wild Wednesday" storms, although the figure was reduced from some 150,000 overnight as electricity workers battled to reconnect people.
The latest problems pile pressure on Prime Minister David Cameron's government, which has faced criticism for being slow to help people in flood-hit areas.
"We have seen some pretty horrendous conditions," said Tim Field of the Energy Networks Association, which represents energy companies, adding that they were trying to get people back on line as fast as possible.
Britain also faces an economic battering after Bank of England governor Mark Carney said the fragile recovery from recession would be affected as the bad weather hits farming and transport.
"There's a big human cost here and I absolutely recognise that," he told ITV News. "Then there's the disruption to economic activity that we see just through transport, but farming clearly will be affected for some time, other businesses.
"It is something that will affect the near-time outlook." Major General Patrick Sanders, who is co-ordinating the armed forces response that has seen hundreds of troops on the streets, called the conditions an "almost unparalleled natural crisis".
Gusts approaching 160 kilometres per hour tore at parts of England and Wales overnight, and the River Thames was predicted to rise to its highest level in more than 60 years in places, threatening towns and villages to the west of London.
One man died after being electrocuted while attempting to move a fallen tree that had brought down power lines in Wiltshire, southwest England, the first to be killed in the latest round of storms.
The floods were also spreading, as water filled the historic crypt of Winchester Cathedral in the southern county of Hampshire. The gothic cathedral has the longest nave in Europe.
The weather conditions brought chaos for commuters, stranding a train carrying hundreds of passengers after overhead lines came down in Yorkshire, northern England.
The Met Office national weather service issued a red warning -- the highest threat level -- for "exceptionally strong winds" in western parts of Wales and northwest England.