Dukes in the United Kingdom
Duke, in the United Kingdom, is the highest-ranking hereditary title in all four peerages of the British Isles. A duke thus outranks all other holders of titles of nobility (marquess, earl, viscount and baron).
Lord of Parliament
The peerage of Scotland differs from those of England and Ireland, in that its lowest rank is not that of baron. In Scotland, the term "baron" refers to a feudal baron, considered to be a minor lord who is not a peer, approximately equal to a baron in some continental countries. The Scottish equivalent to the English baron is the Lord of Parliament.