This study, by petroleum geoscience team at the BGS, was created as part of the 21st Century exploration Roadmap (21CXRM). The petroleum geoscience team worked with the UK North Sea Transition Authority (NSTA), Oil and Gas UK and a consortium of over 45 oil companies to evaluate the remaining petroleum potential of previously overlooked or unfashionable areas of the UK Continental Shelf.The 21st Century Exploration Roadmap (21CXRM): Palaeozoic Project is part of the UK Government's endeavour to maximise the economic recovery of hydrocarbons on the UK Continental Shelf (UKCS), in response to the Wood Review.A study of the Palaeozoic of the UKCS was one of the first projects to be implemented as part of the 21st Century Exploration Roadmap. Multidisciplinary studies further defined the Carboniferous and Devonian petroleum systems focused over and around the Mid North Sea High and northwards to the Orcadian Basin/East Shetland Platform. In the wider Irish Sea area, the focus was the Carboniferous play.Coinciding with the release by NSTA of the UK Government seismic across and around the Mid North Sea High frontier area, project results have been delivered digitally to project sponsors. They include seismic, well and gravity interpretations along with burial/uplift/maturity modelling, source rock geochemistry studies and palaeographic reconstructions to inform the location of prospective Carboniferous and Devonian plays. Onshore data and knowledge has been incorporated.The results were published under the Open Government License in March 2017 and are loaded to the BGS Offshore GeoIndex. Users should note that:These outputs are at a regional scale, created for project specific purposes and so should be used appropriately.They are not BGS corporate products, but peer-reviewed project outputs.