The peer's heir apparent will sometimes be referred to as a viscount, if the second most senior title held by the head of the family is a viscountcy. For example, the eldest son of the Earl Howe is Viscount Curzon, because this is the second most senior title held by the Earl.

However, the son of a marquess or an earl can be referred to as a viscount when the title of viscount is not the second most senior if those above