Lancashire in northwest England and Yorkshire in the northeast were the worst affected, with environment officials issuing more than 300 alerts in those areas, including 20 warnings of possible deadly floods.
In some areas water reached the lower windows of houses and shops, and in others cars had been abandoned after narrow country roads had turned into fast-flowing streams.
Underscoring the severity of the deluge, the government's emergency COBRA committee met on Christmas day to tackle the crisis, with officials under pressure after similar flooding earlier this month in northwest England.