Children taking Dad's surname- every man's right?

Who has the ultimate say, in your opinion, when it comes to choosing a child's surname? Is it the father? Why? How did you choose if you were in this situation?

I was reading at the weekend that the Duke of Edinburgh was very angry at not being able to give his children his surname. and I have to admit I do feel for the guy, especially given this was a lont time ago! But the situation is far more common now (very modern, ma'am!)

I know my ex saw me giving Alex my surname as a direct attack on his masculinity, race and fatherhood and he tried all sorts of methods, legal, bullying, harrassment, threats etc, to make me change it (quite the wrong tactic to use with me, I would have been  more than willing to consider his side but I don't do threats or bullying and I dug my heels right in!) Later on though I felt a little sympathetic to him, although not enough to do anything about it, he'd disappeared by then anyhow.

So what do you think- and men especially, would you consider it disappointing or emasculating if your children didn't bear your surname? How important would it be to you?