It's not just the placenames where that happens you know. Think of "Cholmondely" (my spelling might be off, but it's pronounced something like "Chumlee". Bet you wouldn'te have guessed that from looking.

Recently when people mention this, I get that Aeryn quote in my head when she's trying to learn English - along the lines of it should be easy because there's only 26 letters, but then they change. I think it sums up the stupidity of pronunciation of English quite well.