Dunkirk

I’ve ordered a copy of Ships of the ’45, which deals especially with the naval ships chasing Bonnie Prince Charlie. Looking into the naval situation during the Stuart kingships in more detail I found Dunkirk had been well known in those days. At first I felt it was too far up the Channel to effect major trade but then realised that a major part of trade in those days was around the North Sea and through the Channel. The Mediterranean is romantic but the hard trade, iron ore and timber, was around the North Sea. Operating from the Spanish Netherlands, the Dunkirkers were a pirate group, backed by the Spanish, and hiding behind the protection of the sand banks and shoals that made navigation difficult in the area. According to the literature, the Dunkirkers developed the frigate as a fast nimble vessel ideal for the tricky waters they had to negotiate. I’d always thought of privateers picking off the odd vessel but it seems that in 1621 they were picking off 229 fishing and cargo vessels a year from the Dutch and between 1621 and 1628 they had taken 522 English merchant ships and had become a major diplomatic problem needing the cooperation of Dutch, English (Charles 1), and French to sort out. I can see Hornblower in this.
Where was the Navy?