Flooded homes in south-east England are being evacuated and thousands more are at risk after the River Thames burst its banks.
The Environment Agency issued 14 severe flood warnings - meaning lives are at risk - for the Thames in the counties of Surrey and Berkshire to the west of London.
Some areas are already under water, including parts of the Great Windsor Park, near the Queen's castle at Windsor, which itself is built on higher ground.
London itself is protected by the Thames Barrier, although a suburb to the south of the capital, Croydon, announced plans to divert rising floodwaters caused by heavy rain away from homes and businesses by pumping them into a pedestrian underpass.
Fire crews, who have been rescuing people from their homes in Staines, told the BBC they have never known waters so deep or a flood rescue operation on this scale. In Windsor, Councillor Colin Rayner pleaded for help from police and the army.
Parts of the southwest of England have been under water for weeks after the wettest January since 1766, with more bad weather expected over the coming days.
There has been a growing tide of criticism at the official response, which has erupted into a full-blown political row, AFP reports.
Many people in Somerset, one of the hardest-hit counties in the southwest, blame the devastating floods on the failure of the Environment Agency - a government body - to dredge local rivers.
Communities minister Eric Pickles joined the attack on Sunday, suggesting the government "perhaps relied too much on the Environment Agency's advice" on flood prevention.
Chris Smith, the head of the Environment Agency, hit back on Monday and accused ministers for holding back vital funds.
The Prime Minister David Cameron last week announced £130 million in extra funding for emergency repairs and maintenance.
Mr Cameron paid his first visit to Somerset, where the Royal Marines have been deployed to help with sand-bagging, on Friday and on Monday was due to tour storm-affected areas in the southwest counties of Devon and Cornwall.