The London Tornado of 1091 is the earliest reported tornado in England, occurring in London on Friday, 17 October 1091.[1][2] It has been estimated by modern assessment as possibly a T8 on the TORRO scale (roughly equivalent to an F4 on the Fujita scale) making it one of the strongest recorded tornadoes in the British Isles, alongside the 1666 Lincolnshire tornado,[3] although this estimate is based on reports written 30 years later.[4]
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 so that only 4 feet (1.2 m) protruded above the surface.[4] Other nearby churches were demolished by the tornado, as were over 600 mostly wooden houses. For all the damage, there were just two known fatalities in a population of about 18,000.[4][3][5] The tornado is mentioned in chronicles by Florence of Worcester and William of Malmesbury, the latter describing it as "a great spectacle for those watching from afar, but a terrifying experience for those standing near".[3]