The Queen has not failed in her duty. Her duty is to rerpresent England to the rest of the world. She has no power over the political machinations of the country. She is a figurehead.
I believe the Queen, herself, has been a wonderful role model and has barely put a foot wrong for the length of her reign, which still goes on. However, she has no political power, whatsoever. And, she does not run the Church of England. She is, again, a figurehead of the Church; but, the clergy of that church makes the decisions.
Do some ‘research’ her duty is ‘protector of the faith’... She has failed abysmally given what comes out of her progeny’s acts and mouths.