Ref the North Sea, there is quite a bit more of it to gain moisture than the Irish Sea. The beafy showers from the Irish Sea would require specific conditions, inc. wind speed and direction. If drawing directly down from the Atlantic and through the North Channel, Manchester / Cheshire / Staffs can do well in this set up. Orographic augmentation kicks in quickly over north west England, often allowing light / limited shower activity at the coast to build into more meaningful showers quite quickly - benefitting Huddersfield more than Rochdale!