Undertaking lanes are common in Ireland - a hard shoulder is often provided on the lefet, and slow moving vehicles will move into this to allow faster traffic to pass (I think this is usage rather than law). Loud hoots from everybody on the road usually means that someone's got married and is in a wedding car. It can also mean that your own sports team has won and you're on the way home. Signposts are not as frequent as you would hope, and in country areas a sign post may have twenty or thirty signs fixed to it.

Stu