[2] The original territory of the diocese first became a political unit in the reign of King William Rufus (1087–1100), who made it into the Earldom of Carlisle, which covered most of the counties of Cumberland and Westmorland.

The reigning papal legate, Philip of Dreux, punished this action by exiling the canons and appointing Hugh, Abbot of Beaulieu, a good administrator, as bishop.

It was important to the English government to have a reliable prelate at Carlisle, as they constantly looked to the bishop to attend to Scottish affairs, negotiate treaties, and generally play the part of diplomat.

A fresh beginning was made by the energetic Bishop John de Halton (1292–1324), a favourite of Edward I, and for nearly a hundred years the building of the present choir proceeded, though with many interruptions.

Bishop John Kirkby took an active role in Border military actions, defeating a Scottish raid in 1345 and commanding English troops at the battle of Neville's Cross in the following year.

The subsequent bishops were scholars, frequently employed in negotiating truces and treaties with Scotland, and several of them were Chancellors of Oxford or of Cambridge University.

Among this generation of scholar diplomats was Cardinal Thomas Wolsey's friend, John Kite (1521–1537), who remained faithful to his master, and who supported him in the poverty of his latter days.

After Ogelthorp's deprivation and death, Bernard Gilpin was to succeed him in Carlisle but he refused though much pressed to it, the Bishopric was conferred on one John Best, who was consecrated 2 March 1560.