This Natural History Museums (NHM) digitisation project has produced 7217 georeferenced master sites representing the collection localities for approx., 500,000 NHM Lepitoptera specimens based on label transcriptions. The data set contains the following information; Continent, Country, ProvinceStateTerritory, DistrictCountyShire, Precise Location, Island Group, Island Name, Sea Gulf, Latitude, Longitude, GeoreferenceExtent Kms, Department. This structured file aims to provide a clear repeatable locality classification and thus avoid data duplication. Specific confidence limits for the data can be inferred from the GeoreferenceExtent field which gives a numeric approximation for the accuracy of the georeferenced master site. The georeferencing process aimed to rationalise and to make accurate master site records. This process specifically targets avoiding creating multiple sites records for the same location. To explain this further we might have two different sites that are the same place, one is spelt differently to the other, Eastbourne or eastborne. The Georeferencing and transcription process allows us to merge the specific site records (after the image label and has been looked at, to see if they are the same location), into one master site location and to use Google Maps to define a calculated centroid for Eastbourne and an accuracy assessment of the locality data, which equates to a radii covering the city bounds of Easbourne (as we do not know where the specimen was collected within Eastbourne, and can only rely on the data provided by the label, therefore Eastbourne becomes the master site record and eastborne is assigned to the Master site record, thus avoiding duplication of data).