Fixed-term Parliaments Bill

Can the noble Lord, Lord Marks, explain to me, because I listened to the logic he was developing, how changing a system of voting for a Chamber of Parliament, where that Chamber is already elected, is a greater change than introducing a system of voting for a Chamber of Parliament which is not elected at the moment? I raise this as somebody who is in favour of reform—I do not want to be dismissed as somebody who is not—but I find a real fault-line in his argument, unless he is about to conclude that he thinks there should be a referendum on Lords reform.