Fleet Prison and Rules of the Fleet--title [13 June 2015]
Why not "Liberty of the Fleet" which is used first in the article you are quoted?
There are "liberties" all over England, not a word I can define immediately, but certainly one used in certain circles (church and law) up until about 1850. I think it means something like outside the authority of the nearest logical authority. Extra-parochial falls into the same barrel. Wikipedia on "Liberty (division)" helped to get my head around it.
--Goldenoldie 11:15, 13 June 2015 (UTC)