[3][4] In October 1813, at Lambeth Palace, he was consecrated Bishop of London, a post he was to occupy until 1828, when he became Archbishop of Canterbury.

As archbishop, Howley was their spokesman, and his heart-felt opposition to the Great Reform Act led to his carriage being attacked in the streets of Canterbury.

At 5.00 a.m. on 20 June 1837, accompanied by the Lord Chamberlain, the Marquess Conyngham, the Archbishop went to Kensington Palace to inform Princess Victoria that she was now Queen of the United Kingdom of Great Britain and Ireland.

During his career, he initiated the renovation and rebuilding of: his official house at Oxford, his town residence while Bishop of London (32 St James's Square), Fulham Palace (also while he was Bishop of London), and finally, extensive renovations to Lambeth Palace.

This last project was a virtual reconstruction of the Palace carried out by Edward Blore, the work beginning after 1828 and done mainly in the Gothic Revival style.