This data repository contains all raw data files for permeability measurement, X-ray diffraction (XRD) analysis, high resolution SEM backscatter images and mercury intrusion data files for core material obtained from the Cropwell Bridge (Cropwell Bishop) borehole [SK63NE/28]. This core material is stored at the British Geological Survey, Nottinghamshire. This study presents a comprehensive experimental characterisation of gas permeability, mineralogy and microstructure through a continuous ~ 200 m cored succession of the Late Triassic Mercia Mudstone Group. More than 700 laboratory measurements of horizontal and vertical gas permeability were acquired from 18 samples over a wide range of effective pressures representative of burial conditions. Samples of core were selected intersecting the Tarporley Siltstone, Sidmouth Mudstone, Arden Sandstone and Branscombe Mudstone Formations of the Mercia Mudstone Group. Samples are taken from current day depths between 16.3 and 185.4 m. A total of 18 samples have been analysed. Details on processing methods and the file naming system can be found in the readme file - Jones_2026_supplemental_readme.docx file. SEM images were taken in the Scanning Electron Microscopy Shared Research Facility (SEM-SRF), available as high resolution .tif files at magnifications 150x, 250x and 500x. Mercury intrusion porosimetry data was undertaken in the School of Earth and Environment, University of Leeds, available as .csv files Permeability data was undertaken in the Rock Deformation Laboratory (RDL), University of Liverpool. Python processing script (.ipynb) and raw data files (.csv) are provided. XRD analysis was undertaken as part of the Diagenesis Research Group, University of Liverpool, available data as .xrdml and .hpf files for clay separate and whole rock analysis.