Now Neil has information overload now.
It may seem to some a bit odd our system because the PM is the leader of the party in power and not independent and is therefore answerable not just to voters and MP's but also to Parliment. Our esteemed American members will correct me if I am wrong but the President can find it arkward to get legislation and bills through congress if his own party is the minority. So in someways we are better of but also worse off by the same token some European countries have it more complicated with their Presidents and Prime Ministers serving longer terms between elections with more trouble changing them in a non general election senario than we ourselves have.