The London Tornado of 1091 is reckoned by modern assessment of the reports as possibly a T8 tornado (roughly equal to an F4 tornado) which occurred in London, England. Britain's earliest reported tornado, it occurred on Friday, 17 October 1091, killing two. The wooden London Bridge was demolished, and the church of St. Mary-le-Bow in the city of London was badly damaged; four rafters 26 feet (7.9 m) long were driven into the ground with such force that only 4 feet (1.2 m) protruded above the surface. Other churches in the area were demolished, as were over 600 (mostly wooden) houses.

• http://en.wikipedia.org/wiki/London tornado of 1091