Firstly, Tony Blair is not gay (not that it matters). Secondly, he serves under the Queen, thus she is our ruler.
However, it would appear that you are suggesting Mr Bush is gay. Hence: "why not? The Americans already have one."
I am sure the Germans are indeed ready for a gay leader, but he has ruled out the move in favour of Kurt Beck.
http://en.wikipedia.org/wiki/Klaus_Wowereit