Don't know - we also don't pronounce plenty of other letters too. Plumbing is plumming not plum-bing. Also apparently the word solder comes from Middle Englis

Don't know - we also don't pronounce plenty of other letters too. Plumbing is plumming not plum-bing. Also apparently the word solder comes from Middle English 'soudure' which doesn't even have an L in it.