A few high fantasy series do not easily fit into Gamble's categories. For example, J. R. R. Tolkien's The Lord of the Rings is set in the primary world of Earth in the ancient past, and he adamantly disagreed with anyone who thought otherwise. According to Tolkien, he had set it in the inhabited lands of geographically north-west Europe. The Professor himself disagreed with the notion that his stories diverged from reality, but rather defended his position that the essentials of that abiding place are all there (at any rate for inhabitants of N.W. Europe), so naturally it feels familiar, even if a little glorified by enchantment of distance in time. Nevertheless, Middle-earth is sufficiently divergent from reality to be classed as a secondary world and hence high fantasy. J. K. Rowling's Harry Potter series is again set in the real world; however, while the primary setting, mostly the school, Hogwarts, is said to be located somewhere in Scotland, it is physically separated from the real world and becomes a world-within-a-world. Hogwarts is therefore as much of an alternative world as C. S. Lewis' Narnia, which means that both series are in the high fantasy subgenre. Similarly, Philip Pullman's His Dark Materials is largely set in an alternate Oxfordshire, a real location, but the fact that it is an alternate world at all places it in the high fantasy subgenre.