The Origins of the F Sound in Old English

In old English, the word was spelled W-I-F and it was pronounced weaf with an F sound at the end. The Norman French got hold of those words after 1066 - they decided to fix those spellings. By that point, during the period of Middle English, the V sound had fully developed within French. So all of those old English words got new spellings with a V instead of an F. Some linguists think that a modern word like OF is one of those stragglers. Its current pronunciation may be the same as it was in old English.