Paddington isn't actually speaking EnglishThe books present an example of Fridge Logic, if he's from Peru, shouldn't he speak Spanish? The explanation is this, Paddington doesn't know Spanish because he speaks a different language from the rest of Peru (let's call it Darkest Peruvian) which by sheer coincidence is exactly like English, explaining how Paddington and Aunt Lucy are able to converse in English.
Paddington is supposed to be a hero to evacuees who went unclaimed after the war.He arrives back from somewhere far away and unfamiliar after living with a relative he had never met before who wanted shot of him ("Aunt Lucy always wanted me to emigrate when I was old enough"). He wears a tag that asks a stranger to take care of him. He returns to the train station where he must have set off from, and there's no one there. About 40,000 of the WWII children came back to find that their parents had gone.