I don't get how first class post can be considered as served. At the minute were missing loads of mail we were expecting months ago, hospital letters we know get sent on a specific day arrive weeks later on average.
I got stung with a parking fine that had tripled in price due to me “ignoring them” when the letters never turned up, they wouldn’t even discuss it on the telephone or entertain the idea that their mail hadn’t arrived, if first class post with no signature is considered 100% reliable from a legal standpoint that probably explains why