mining and local history books can be a valuable source of information about workings that may not appear on maps, because many small mines and trial workings are not recorded. Local sources of information maybe important for example, farmers may know of old workings on their land. Similarly cavers, mining research/history groups, industrial archaeology groups and others with interests in underground structures maybe able to help. If extensive underground sites, such as caves or mines, are to be explored for bats, safety must be a prime consideration. Simple rules for safety underground are given in Chapter 2 and a model risk assessment for entry into disused mines maybe found in Appendix 8. Even relatively small structures such as ice-houses or lime-kilns can be dangerous places if they are in bad condition so always proceed with caution and be prepared to abandon the visit if the structure looks dangerous. Always observe common courtesies when searching for new sites. Seek permission from landowners before going on their land and check that entering a site is not going to interfere with other people’s interests. Some sites are used for storage, dumping of rubbish, mushroom-growing or water supplies and their owners are naturally sensitive about allowing others access.