Most people think that it’s because a lot of characters in
British movies are unable to swim. That doesn’t make much sense to me, as it
doesn’t explain why he didn’t learn to beforehand. I see it more as a metaphor
for his own arrogance.

England thought very highly of his royal navy, and we know
full well that he loves to gloat. Because of his self-perceived “invincibility”
on the waters  – yes, I’m referring to one of his character songs, sue me – he probably
didn’t feel the need to learn how to swim.