It's all the fault of the Brits!

Interestingly enough, all alphabetic writing systems start out, more or less, by transcribing sounds phonetically (or more accurately, phonemically). But, as I and others have constantly said, language changes. Unfortunately, some societies treat their orthographies more conservatively than others do, and as the years pass you get whacky spelling systems like the English, French, Gaelic, or Tibetan, where the actual sounds of the language and how they are written get more and more out of sync.

For the record Cholmondley was probably pronounced closer to its spelling about a thousand years ago.