In 1974 the Tornado and Storm Research Organisation (TORRO), initially called the Tornado Research Organisation, was founded by Terence Meaden to study reports of previous and new tornadoes as well as to conduct site investigations to confirm or disprove reports across the UK. These site investigations also allow further details to be built up around events, such as estimated wind speed based on damage caused, track width and track length. Since its inception TORRO has been cataloguing tornado reports extending back as far as 23 October 1091, when the first recorded tornado was noted in central London (Brown et al., 2012). Tornadoes in the UK are always rated, where possible, using the T Scale as set out by Meaden in 1972 (Meaden, 1985), and included in Table 1 for reference. These ratings can span different scale numbers such as T4/5, where tornadoes are on the borderline between two strengths, or for older events, where less information is known. Figures for older events can also be appended with ? or + where these are the best estimates from historical accounts of the time and indicate that damage is believed to have possibly reached a certain level or exceeded a certain level, respectively. The scale also includes track length (L Scale), track width (W Scale) and track area (A Scale) categories, which require a full site investigation to ascertain. These site investigations are all carried out by volunteers, many of whom are members of TORRO. Tornado totals collected by TORRO cover the UK as well as the Channel Islands and Isle of Man, as per previous studies (Reynolds, 1999), the latter due to their historical connection to the UK as Crown Dependencies, out to a distance of 30km offshore: chosen because that distance can be seen from land on a clear day. For convenience this combined area is referred to as the United Kingdom in this paper. Tornado totals include all confirmed (where there is conclusive evidence of a tornado from observations or damage characteristic of a tornado) and probable (where there is reasonable evidence of a tornado but not enough to be certain), but not those that are merely possible (where a tornado was reported but there is insufficient evidence to count as such) reports. A Tornado Day is defined as a day in which a tornado occurs, from 0000 to 2359 UTC. Once checked and verified, reports of tornadoes are published by TORRO in The International Journal of Meteorology (The Journal of Meteorology prior to 2006). All tornado ratings referred to in this paper are the maximum intensity reached during the lifetime of a tornado. Confidence intervals of 95% are given with all mean figures, which indicates that the actual population mean is within the range calculated from the dataset with a confidence level of 95%. During on-site investigations after a tornado the T-scale category can be estimated based on the general level of damage caused. The following descriptions are used as guidance during such investigations: