the DUCHY of Burgundy, the one ruled by Charles the Bold, is the one referred to in this WI question.
so let's say Charles wins the Burgundian Wars, and his duchy (or more likely, Kingdom after this) survives with the Low Countries, present day Burgundy, Lorraine, and some of northeastern France.
I know Burgundy got along very well with England at the time, so if Burgundy still existed, would England keep Calais for a lot longer, possibly long enough to be comparable to OTL Gibraltar?
...