Sui generis
In local government, a "sui generis" entity is one that does not fit with the general scheme of local governance of a country. For example in England, the City of London and the Isles of Scilly are the two "sui generis" localities, as their forms of local government are both (for historical or geographical reasons) very different from those of elsewhere in the country. 
In a press conference during which reporters were trying to analyse his political personality, Huey Long said, "...say that I am "sui generus", and let it go at that."
History of Sussex
Borough-English was the custom that lands should descend to the youngest son or daughter, or, in default of issue, to the youngest brother of the deceased. The name originated from a case in Nottingham in 1327 when the English borough, or part of the town, held to ultimogeniture, the French (Norman) part to primogeniture. In Sussex, inheritance by Borough-English, could still be found on 134 manors after 1750.