In Permian Rotliegend aeolian sandstones in the Dutch sector of the North Sea, kaolinite dominates over poorly crystallised, pore‐lining illite in areas of shallow burial. Fibrous, bridging illite dominates over kaolinite in the areas of deeper burial.This distribution of diagenetically formed interstitial clay minerals coincides with a regional permeability trend. Higher permeabilities occur in the area where kaolinite dominates over poorly crystallised, pore‐lining illite; lower permeabilities occur in the area where fibrous, bridging illite dominates over kaolin