During the reign of King Edward VI, his Catholic older sister Mary made repeated, and futile attempts to flee to the Continent to live in exile with her cousin Emperor Charles V, so she could at least maintain her Catholicism. However, Edward refused to let her go each time. What if Mary had successfully "escaped" but then died soon after arriving on the Continent, making Elizabeth last heir to the Tudor dynasty. When Edward dies as in OTL, Elizabeth becomes Queen in 1553 of a strongly Protestant country, dominated by the increasingly radical Archbishop Cramner. How does England develop?
I've been researching this stuff for my own timeline, so here we go:
to begin with, it's not certain that Elizabeth inherits directly. Edward's will in our timeline excluded both sisters Mary and Elizabeth and the Scottish descendants of his aunt Margaret Tudor (I got the name right that time) in favor of the descendants of his other aunt, former queen of France and Duchess of Suffolk, Mary Tudor Brandon. This is the explanation for why they attempted to install Lady Jane Grey as regnant queen in our time line. Now, ostensibly all this is out of fear of Mary's Catholicism, but how much of it might be the desire to continue a string of easily manipulable successor-children in the mold of Edward? Institutionally speaking, regency always has a constituency.
Assuming the most straightforward option, that it does go to Elizabeth, that she sits on the throne of a more strongly Protestant country is not to be just assumed. Her position in her early years is strengthened by virtue of the backlash against Mary, and remember that Mary not just because she was Henry VIII's actual daughter, but to some degree also because of her religion, had enough support that she had enough support to overthrow Lady Jane Grey and her powerful backers. The Henrician Reformation, remember, was still only twenty years old in 1553. Thomas More's blood had scarcely had time to dry on the executioner's axe. So there is still a Catholic country there to some degree, under the surface. And so I actually see a more cautious, and less Protestant, Elizabeth. She might even feel the need to give in to one of those marriage proposals.
In the long run though, I'm not sure, without more happening besides, having Elizabeth rule from 1553 instead of 1559 gets you that much difference.
Other than perhaps a Golden Jubilee. But even small differences then can have big consequences down the line.