YNCS raises the best point so far on the subject of effects on British history: it's not down to the overall quality of any one harbour, but rather the fact that the English coast has good, sizeable natural harbours at short, regular intervals all along the Channel coast from London in the East to Land's End at the West. *
This was of major importance from the 16th century through to the late 19th century. Whenever the weather in the Channel turned rough, British vessels could always rely on somewhere near, safe and friendly to ride out the storm.
Compare and contrast the Channel and Biscay coastlines of France, which have some very good harbours, but widely spaced apart. Or the northern coast of Spain, which has little in the way of secure roadsteads.
This factor contributed greatly to the victory over the Armada, the ability of the Royal Navy to mount a cripplingly effective blockade on France for years at a time, and the simple fact that the Channel became a British-controlled chokepoint for several centuries.
* people tend to focus a lot on Portsmouth, but for a large part of the French wars Carrick Roads (Falmouth) was almost as important strategically, for its position as a very well sheltered deep-water harbour at the very edge of the western approaches. And if you couldn't reach Portsmouth or Falmouth, there was always Torbay and Weymouth in between...