I would like to take back my vote for George III and submit
Henry VIII as my vote. Before people jump down my throat about having been a bad leader, consider the fact that NO monarch had a clean slate. Even Elizabeth and Victoria have a tainted reputation when it comes to certain events within their lives, so to say Henry VIII is not leaderhead material is rediculous.
I think his unification of England and Wales (and the resulting "official" language of Wales being English and not Welsh thereafter) laid the foundation for a strengthened English state, one that would later expand to form the United Kingdom (not under Henry VIII of course). He also was the first king of England to officially call himself king of Ireland, the standard title having been lord of Ireland prior to this. This was due to the fact that the Irish regarded the King of England as an overlord ruling in the stead of the pope, who was the person they saw as their actual leader.
I also think his infamousy for marrying (and executing) many wives adds to make him more interesting than other possible leaderheads.
Furthermore, he was a poet, writer, artist, and great supporter of the sciences. He is known as the perfect example of a Renaissance man. He in fact, was the first English monarch to show interest towards the newly discovered American continent, an extremely important point in England's history.
One of the biggest effects of his reign was the founding of the Anglican church...the reason may have been egoistic (doing it only to get his first wife out of the way to marry another) but the fact stands that this had considerable impacts on England's future, changing the state church from a catholic to a protestant one.
Another extremely interesting fact is that he is also the father of the later famous Queen Elizabeth I (the one in the original Civ game). It would be extremely cool to see the two in a game together (though unhistorical).
Last aspect I want to mention is the fact that his persona and appearance make him an extremely interesting character, something that raises him above the rest. I think he would be a really good choice for England's new leaderhead, and he ACTUALLY has something going for him in terms of effects on his country...King Richard I, while extremely famous...is only famous for abandoning his country during the crusades (we Germans captured him on his way back to England hehe

) and putting them in great debt, with no overall success to show for it.
I hope you don't forget to note my change of vote Shiro, since I can't do it via the poll anymore.
EDIT: Haha, while I was writing this, it seems Civinator also suggested Henry VIII...no problem though, that makes
2 for good ole' Henry!!!