if the first child of the duke and dutchess of cambridge is a daughter, she could become queen.hey wouldn't have to wait around to have a son. he also wants to scrap a ban for anyone who marries a roman catholic. the monarch here is the head of the church of england. martha: two of the greatest leaders on the thrown, the two queen elizabeths, both women, but they didn't have a big brother. so you have charles, then you go onto the child of kate and william. a lot of royal families have gone to this model where whoever is born first gets the spot, right? >> reporter: exactly. so england will fall in line with others. it won't be easy, however. david cameron wants to appear modern and curry favor with women in england. but what he's got to do is legislatively expensive for the time standpoint. 6 different acts of parliament have to change to get this to happen. he also has to get 15 other countries in the u.k. commonwealth to go along with this. past prime ministers brown and blair tried to do this and they failed. first up, prince charles, then prince william succession would sta