Catherine de Medici in England?

So, Horny, you seem to be suggesting that the Protestants in England would not have had the power to prevent another Catholic monarch after Mary Tudor's fairly early death at 42, despite Mary Tudor's unpopularity and the unpopularity of the Spaniards who were effectively "colonizing" England after she married the immensely powerful Phillip II of Spain. I think you're probably right, since the attempted uprisings against her failed so miserably. The monarchy was an extremely well respected institution in sixteenth century Europe, and lineal descent by blood was of paramount importance. So, since after Mary Tudor's death, with no Elizabeth around, Mary Stuart is the closest legitimate blood relative, I think she's very likely indeed to get the prize, isn't she? Then we have the very interesting prospect of French catholic colonists replacing Spanish catholic colonists in both England and Scotland. What would that be like, exactly? True, Mary Stuart's French husband, King Francis II dies in 1560, but, with the formidable Catherine de Medici acting as regent for the new French King, is this awesome woman likely to give up England and Scotland? Hardly likely. And, the French approach to dealing with the Protestants was much more complex, subtle and, ultimately effective than the Spanish approach. The Spanish hardly had to deal with Protestants at home. The Iberian Peninsula was threatened by Moors and Turks, good Christian Catholics had to stick together! And, all of Catholic France stood between Spain and the Protestants in Switzerland, Germany and the low countries. In contrast, France was on the very front line of the war between Catholicism and Protestantism, a war they fought for centuries, until religion ceased to be a major factor in European politics. France used every approach possible to deal with Protestantism -- full tolerance, limited restrictions, Inquisitorial type persecutions, genocidal extermination! Sometimes, the French would go from one extreme to the other, in a most unpredictable fashion. Witness Catherine de Medici's immensely successful and totally unexpected St. Bartholomew Day Massacre! So successful in bringing to a dead halt Protestantism's advances in France, that it is celebrated to this very day in the Vatican in a great painting showing Charles IX justifying the act to the French Parliament. https://en.wikipedia.org/wiki/St._Bartholomew's_Day_massacre Why not a comparable massacre in London, as well as Paris? Surely, that would teach the protestant English dogs to heed their master, the Pope! While I'm not sure a full union between England, Scotland and and France was at all sustainable, long term, it seems rather more likely to me that the formidable Catherine de Medici could have largely extirpated Protestantism from England in the long term, with Mary Stuart on the throne. Using extremely ruthless methods of course, far more ruthless than anything the comparatively civilized Spanish Inquisition would have considered. The Spanish Inquisition favored controlled, selective killings. That wasn't enough to control the English, of course! Genocide would have been necessary, and that was a tool the French were quite willing to use in their wars of religion. Remember what they did to the Cathars in Languedoc!