He was principal at Cuddesdon from 1863 to 1873, when the prime minister, William Ewart Gladstone, appointed him Regius Professor of Pastoral Theology at Oxford and canon of Christ Church.

[2] To the world outside, King was known at this time as an Anglo-Catholic and one of Edward Pusey's most intimate friends (even serving as a pall-bearer at his funeral in 1882), but in Oxford, and especially among the younger men, he exercised influence by his charm and sincerity.

A leading member of the English Church Union, King fought prosecutions in lay courts under the Public Worship Regulation Act 1874 (which Archibald Campbell Tait, Archbishop of Canterbury, and the prime minister, Benjamin Disraeli, had secured over Gladstone's opposition in order to restrict the growing Oxford Movement).

[3] In 1885, upon Gladstone's invitation when he again became prime minister, King accepted consecration as Bishop of Lincoln,[1] which he noted had been the diocese of John Wesley.

[4] Although Tait had died in 1882, the Puritan faction continued to voice its objections, including at Lincoln where J. Hanchard published a sketch of King's life, criticizing his Romish tendencies.

[8] In his "Lincoln Judgment", he found against King on two counts–ruling that the mixed chalice, altar candles, eastward-facing celebration, and Agnus Dei were permissible but that the sign of the cross at both the absolution and blessing were not[7]–and also required him to conduct the manual acts during the prayer of consecration in the service of Holy Communion in such a way that the people could see them.

[12] Later, many of King's liturgical practices became commonplace, including making the sign of the cross during the absolution and blessing, and mixture of elements during the service, for which the criticisms had been upheld as an innovation.

The calendar of the Church of England remembers King with the status of a "lesser festival" or "black letter day" on 8 March, the date of his death.