Oh, I don't think you can make a case that he got into our world. In fact, no Narnian ever visits our world, except for King Caspian ever so briefly at the end of Silver Chair, and then only after he's died in Narnia. I think Lewis just forgot to mention him again. Remember, there was lots of activity over in Lantern Waste, and most of it didn't result in traffic to this world. Traffic between the worlds was closely regulated by Aslan. He only allowed it from our world to Narnia in very rare instances; He never seemed to allow it from Narnia to our world (for Narnians, that is.)