Could have fooled me! I mean, let's look at the evidence:
- The young prince growing up away from his throne, for his own safety - check
- Grizzled mentor who tries to prepare him for the throne, but doesn't always tell him the whole truth - check
- Prince Arthur - check
- A quest - check
- A Lady in the Lake - well, a Queen in the Sea at the centre of the world, close enough! - check
- A magical sword in a stone - ok, it's an all-powerful trident in a fossilized skeleton's hands, but close enough - check
- An impressive (future) queen who stands by her (future) king - check
- "One true king" - check
- Main enemy is a family member - younger brother vs nephew? We'll take it! - check
See what I mean?!