A set of 11 1:25 000 scale OS sheets annotated with the outcrops of the principal veins of the North Pennine Orefield, prepared as aids to the revision of the BGS Geology of the Northern Pennine Orefield memoir, vol. 1: Tyne to Stainmore, published in 1990. Some mining data are also included on the maps. The original data provided by Sir Kingsley Dunham were transcribed onto the 1:25 000 scale sheets to aid in adding grid references to the revised memoir. The data were mostly originally compiled from Dunham's detailed Second World War investigations of the orefield, together with some of Dunham's original 1930s PhD work. These records came from Geological Survey 'mining slips', which were on County Series sheets. For the 1990 revision of the memoir, new data were incorporated, derived from more recent mapping and a large volume of post-1940s mining and exploration data, together with the results of major advances in stratigraphical, structural, mineralogical and geochemical interpretations. The maps depict all of the major mineralised veins as black solid lines. The extent of replacement 'flat' orebodies are generally not shown, though the comparatively modest 'flats' associated with the Windshaw Bridge and Browngill veins at Tynebottom (sheet NY74) and the famous Boltsburn flats at Rookhope (sheet NY84/94) are indicated: the extent of the substantial area of 'flat' mineralisation around Nenthead is not depicted, almost certainly due to the difficulty of so doing due to the closely-spaced network of parent veins. Major, mostly un-mineralised, faults relevant to the descriptions and interpretations of the mineralisation are depicted as broken black lines. Other faults, depicted on BGS mapping, are not generally included. Only those details of mining, such as shaft and adit positions – shown in red by the use of standard BGS symbols – included on Dunham’s Mining Slips are recorded here. There are countless other shafts and adits across the orefield, some of which are mentioned in the memoir text but not depicted on these maps. Broken red lines depict significant underground cross-cut levels and drives which are described in detail in the memoir text. Countless others were not depicted by Dunham and are not shown here. Notes in red, copied from Dunham, are mostly self-explanatory and indicate the names of individual mines, shafts and adits. On his ‘Mining Slips’ Dunham made brief notes on some of the most obvious primary minerals he observed on some mine dumps. These are not included on these 1:25 000 scale maps. Many of these dumps have since become overgrown, and some have been removed. Reference to the ‘Mining slips’ may therefore be useful, though subsequent detailed mineralogical studies have revealed a much greater diversity of mineral species than was then recognised and which gives important clues to the nature and origins of the deposits. There is a rather extensive more recent literature on these.