Unfortunately, they cannot be kept out of it. While it is all very well to campaign for a democratic title to Head of State, monarchists will demand to know what is wrong with the present 'tried & tested' system. Well, it depends solely on blood lines in theory & these can throw up some strange characters. See my score sheet for past monachs on this link.

Rather more importantly, if blood line is so important, we need to be sure we are getting a true blood line for our money. For example, the king with the weakest traditional blood line was Henry VII, who's line included bastards. In the good old Dark Ages, kings were elected & bastards were as eligible as legitimate sons (usually but there were Queen Regants elected as well). However, Henry VII did have a blood line, as far as we know & was the most efficient royal administrator this country has ever had. Things become messier when we contemplate the current royal family &, with the availability of DNA testing, we the people are in a position to demand proof that we are getting a true blood line. We can demand but we will not receive it, as the following family trees demonstrate.

Diana undoubtedly has royal blood but it goes back a long way. If one goes back far enough, we all do (in my case, a very long way to the Kings of Navarre in the tenth century, Sanche Garcias Mitarra II). But prince William is sold as a member of the present royal line....

Thanks to www.throneout.com/images/royal_affairs.pdf for the detail.