In this study, we reveal what can be achieved from modern reprocessing of legacy regional 2D data using modern broadband and depth imaging techniques. We achieve a higher signal-to-noise ratio, improved event continuity and more reliable deeper Cretaceous and Jurassic images. Use of a single 3D velocity model-building method incorporating several 2D seismic lines simultaneously ensures line ties even for 2D regional data. The largest problems encountered were related to the 100 m to 4800 m range of water depths which required a variety of demultiple methods needed to ensure regionally consistent results in the presence of strong 3D effects. We illustrate regional quality control tools used and the removal of some spurious events associated with the original processing flow. We draw attention to some nuances involved in the interpretation of standard difference displays, show the improvements arising from the use of water column function velocities and quantify the additional value of Full Waveform Inversion (FWI) to improved imaging for the project. Improved imaging results will expand understanding of the basins’ geometry and sediment fill and should provide an excellent tool for future industry and academic research in the Irish offshore.