What does the name relate to: sailing, bugs, fish???
Nope, somthing much simpler; the name comes from from the French les roches - the rocks. Just don't ask me how they got a French name though, something to do with the Normans perhaps.
Surprise then, but an afterthought will be that such transformations are really common. As to the French impact – I do know why: the Celtic Britannia likes everything French as the Normans beat the Anglo-Saxons, right Dan?