We know that the Queen did not speak out publicly against atrocities put into place by Parliament enacted policies. Stanislaus and a few others have given legitimate reasons why the British monarchy should not engage in public political debates, or use their apolitical positions as a political megaphone.
We also know that the Queen, though not obligated to do so, had private weekly meetings with whichever Prime Minister was active at the time. What we don’t know is what was discussed during those meetings. Sure, they may have discussed fluff, like what type of tea is best for High Tea, or which of the Queen’s corgis is cutest, but I don’t believe they did. I think they discussed matters of more substance, including humanitarian issues.
Knowing what little I know about the Queen as a non-Brit, I believe the Queen was intelligent and caring. I believe she was aware of at least some if not all of the crimes against humanity committed by Britain, and if she was aware I believe she would have voiced her concerns firmly during her private PM meetings. Did the PMs listen? Did they heed her advice? We don’t know.
If this is the case, did voicing her concerns stop all of the British crimes against humanity? Obviously not, because atrocities still occurred, including the Kenyan concentration camps. What we don’t know is whether or not her private meetings had any positive effect at all. It is not unreasonable to believe that they did have a positive humanitarian effect in some ways on some issues, and no effect in other ways, including the Kenyan camps. Are the failures her fault, or the fault of PMs/Parliament who did not heed her advice (assuming she proffered advice, which I believe she did). I’m giving the Queen the benefit of the doubt and believe she did the best she could while staying in her wheelhouse of knowledge and given abilities, without potentially creating a constitutional crisis, which would no doubt result in no positive effects, nor reduce humanitarian atrocities.
But, you say she could have megaphoned her political concerns publicly, instead of privately. The reason being this had the potential to persuade Parliament to do the right and moral thing, even though private persuasion had no effect. That is a long-shot hope. Maybe it would have helped, but probably not. It would certainly make the Queen look like a white knight in the eyes of the world—look at that wonderful queen who fights evil Parliament in the name of humanitarian justice! But, it would have also created a constitutional crisis with the potential to do more overall harm than good, even with regard to humanitarian efforts.
Members of the Royal Family are closely linked to hundreds of charities, military associations, professional bodies and public service organizations. Some are well known, others are not. Having a Royal patron provides vital publicity for the work of charities, and helps them grow and to be more effective.
Placing the constitution in crisis by engaging in public political debate over singular humanitarian issues (e.g. Kenyan concentration camps) would probably not help those singular issues any more than private meetings, but the resulting constitutional crisis could very well put the monarchy at risk or at least lessen its effectiveness, which could harm the charities they are associated with. Choosing ones battles is the smart thing to do and battling in private is the smart thing for the Royals to do. If the Queen did not try to persuade the PMs in private to refrain from immoral acts, then shame on her. But, I think she did. Did she win all her battles? No. Did she win some? We don’t know, but I think she tried.
Vitriol should be wholly directed at the power brokers who create and implement policies that are crimes against humanity. The Royals are not the power brokers and they should not be political megaphones.