In other words, please treat knights and aristocracy as two separate things in the category tree.
In the DWU, and indeed in real life, there's a difference between a knight and an aristocrat. Obviously, Rose Tyler and Ian Chesterton are both knights, but neither could reasonably be said to be a part of the British aristocratic establishment. Knighthood does not confer aristocracy.
This category has the following 2 subcategories, out of 2 total.