A tsunami in the Bristol Channel could have caused the deaths of up to 2,000 people in one of Britain's greatest natural disasters, experts have said. For centuries, it has been thought that the great flood of January 1607 was caused by high tides and severe storms. It is estimated 200 square miles (520 sq km) of land in south Wales and south west England were covered by water. In a BBC Timewatch programme, two experts have argued a tsunami could have caused the devastation. Eyewitness accounts of the disaster, published in six different pamphlets of the time, told of "huge and mighty hills of water" advancing at a speed "faster than a greyhound can run" and only receding 10 days later.