My summary of the Lydiard method starts with the fact that he recognized that aerobic fitness is the basis of all superior performances. Some people have naturally higher levels of aerobic fitness than most others and don't have to work as much on developing it. Some, and Arthur always mentioned Africans, have a way of life (jogging or walking several miles to school, chasing goats, walking everywhere rather than being driven, etc) that naturally develops aerobic capacity. But most people need to do a lot of work on developing their aerobic fitness and the best way to do that is to run a high volume of miles. One hundred of those a week is a good ballpark figure. But there are people like Kim Stevenson who followed Arthur's ideas quite successfully and never ran 100 miles in a week and there are people like Jeff Julian, Richard Tayler and me (notice how I manage to make myself like these other guys?) who frequently went to 150 and beyond.
Once the aerobic fitness is developed, it's time to balance out your running with types of work that get progressively harder, faster, and more like what you'll do when racing.
Arthur laid out one way of doing all of this in his books. But what Glen, Kim, Nobby, and I are all saying is that once you understand why each of the things he put into his system are there, you can mix and match them to suit your own needs or the needs of whomever you're advising.
Yes, many of us Lydiard folks look at the training of almost all successful runners and say that it looks like the Lydiard method. What we're really saying is that as far as we can tell, that training addresses all of the elements that Arthur thought you needed and does so in a properly balanced way. We don't really know what inspired all of them to train the way they do. But we will tell you that Arthur pretty much standardized the way people train. To try to understand modern training without understanding Arthur's approach is like trying to understand german philosphy without understanding Goethe, or as Malmo's said, understanding physics without understanding Einstein. But that doesn't mean that others can't have original thoughts or adaptions. It just means that they've probably begun understanding training by looking at what someone successful has done and that if you trace that inspiration back far enough, it probably leads to someone who looked at Lydiard.
So briefly, I'd summarize Lydiard by saying, 1. Develop aerobic fitness. 2. Once that's done, begin to introduce training that's progressively more race specific. The addendums to these two steps would be descriptions of the various ways of accomplishing step 2.