We all know that if you play England on Archipelago or something similar, you can make full use of their UA. I've tried that (more than once), and even still I always thought that, unfortunately, England's UA was probably the worst. Then I played on someone's Earth map with True Start positions. That was probably the most fun I've had in Civ V.
The whole of Europe has been settled. Trust me. France, Germany, Spain, the Danes, and even Rome were fighting over it. Africa had mostly been claimed by Askia and Egypt. And of course the New World had been gobbled up by the "natives."
So guess what that leaves for England?
You can found about 3, POSSIBLY 4 good cities on the British Isles. I shudder to think what the Celts would do to that possibility. Anyway, this game was before the expansion pack. So you look for places to settle-- South Africa is a great spot. Though not historically accurate, I settled Madagascar as well. Unfortunately, as India was one of the strongest civs in the game, there was no chance of colonial "settlement" there, so I looked further. For some reason, Siam and Polynesia had not grabbed the East Indies, Australia, or New Zealand. Out go the settlers; Sydney, Darwin, Brunei, Papua New Guinea, and Wellington are founded.
So, what is the geography of my empire again? I have about 8 or 9 far-flung outposts (quickly turning into very large, productive cities) ranging from 30 to 90 tiles from my capital. Think about the historical British Empire-- I had actually managed it quite well simply based on the fact that they were the only places left to colonize. Suddenly their UA made PERFECT sense. With such a far-flung empire, the ONLY security was in fleets. Moving units around would've been a NIGHTMARE without those +2 moves (this is applied to EMBARKED units as well, by the way-- at Optics, your embarked units have 4 moves!). With the new expansion, the threat of melee ships is incredible (have you noticed how the AI loves to spam them?!?!), and even more so to such an empire.
If you're still reading this, try playing England on such a map (King or higher!), then come back with your analysis of their UA. Personally I think it's strong, particularly so in the new expansion. It's not Tier 1, but it's strong enough.