Oh, oh, Shona, I love it! I've never heard of the Cinque Ports...the term, I mean. Here're a couple of things your link says:
The Cinque Ports were first mentioned in a Royal Charter of 1155 and for certain privileges maintained ships that could be called upon by the Crown in times of strife. ...

According to the original Charter, the members of the Cinque Ports had the right to:

"soc and sac, tol and team, bloowit and fledwit, pillory tumbril infangentheof, outfangentheof, mundbryce waives and strays, flotsam and jetsam and ligan".