One way of describing London's relative is location is that it is in the northern hemisphere, on the British islands, in the east-central part of England. This is just one example, however, as relative location is simply a city's location relative to other locations.
Another way to state London's relative location is to say that it's 3,358 miles east and slightly north of New York and approximately 214 miles northwest of Paris. Aside from location in relation to cities, landmasses, mountain ranges and bodies of water can also be used in giving a relative location. By contrast, an absolute location would be London's exact latitude and longitude, which is 51° 30' N / 0° 7'.