Those who are unconvinced that the English Reformation was adequately Protestant need look no further than Calvin’s opinion of the kings for an outside assessment. Calvin dissembles no affection for Henry VIII:
In short, the reformation under Jehu was like that under Henry King of England; who, when he saw that he could not otherwise shake off the yoke of the Roman Antichrist than by some disguise, pretended great zeal for a time: he afterwards raged cruelly against all the godly, and doubled the tyranny of the Roman Pontiff: and such was Jehu.
When we duly consider what was done by Henry, it was indeed an heroic valour to deliver his kingdom from the hardest of tyrannies: but yet, with regard to him, he was certainly worse than all the other vassals of the Roman Antichrist; for they who continue under that bondage, retain at least some kind of religion; but he was restrained by no shame from men, and proved himself wholly void of every fear towards God. He was a monster, and such was Jehu.
Calvin’s attitude toward Edward VI was quite different. As Edward was called ‘our Josiah’ in a letter to Calvin, so Calvin also encouraged him to imitate that young king of Judah in reforming the country according to the word of God.
Yes, Henry VIII was notoriously unreliable in his support for reformation in the Church, and he may have been motivated much more by avarice and power-lust than virtue, but both the Articles of Religion and the Book of Common Prayer are a Reformed representation of the faith. That the English Reformation was directly precipitated by Henry’s desire to annul his marriage with Catherine of Aragón is of little consequence to this reformation’s legitimacy on the whole, because it was led by not just Henry himself but also other men with different – and biblical – goals.