The queen can dissolve parliament.
As I said earlier, it's not the power she has, but the power she denies others. Also the armed forces answer ultimately to her and not any politician. I don't think the Queen is disinterested...she's been there through multiple prime ministers and has vast experience. The thought of a politician in that position makes me shudder...I need only say Tony and Cherie Blair to make any sensible person a raving monarchist.