Watson's clerical preferment after this was very rapid. In 1773, through the influence of the Duke of Grafton, he obtained possession of a sinecure rectory in North Wales, which he was enabled to exchange during the course of the following year for a prebend in the Church of Ely. In 1780 he succeeded Dr. Plumtree as archdeacon of that diocese; the same year he was presented to the Rectory of Northwold in Norfolk, and in the beginning of the year following, received another much more valuable living, the Rectory of Knaptoft in Leicestershire, from the hands of the Duke of Rutland, who had been his pupil at the University. Lastly, in July, 1782, he was promoted to the bishopric of Llandaff, by the Prime Minister of that period Lord Shelburne, who hoped thereby both to gratify the Duke of Rutland, and also to secure an active partisan. Watson, however, proved a very unmanageable bishop, and during the course of his political career was singularly free and independent in his sentiments. One of his first acts was to publish in 1783, 'A Letter to Archbishop Cornwallis on the Church Revenues, recommending an equalization of the Bishoprics.' This he did in spite of all that could be said to make him see that it would embarrass the Government, and at the same time do nothing to forward his own object. And so he continued to take his own way, and was very soon left to do so, without any party or person seeking either to guide or stop him. In 1783 Bishop Watson had married the eldest daughter of Edward Wilson of Dalham Tower in Westmoreland. In the year 1789 he retired from politics and betook himself to an estate which he had at Calgarth, on the banks of Winandermere, occupying himself in educating his family, and in agricultural improvements, especially planting, for which he received a medal from the Society of Arts in 1789. Previous to this, in 1786, his friend and former pupil, Mr. Luther, of Ongar in Essex, had left him an estate which he sold for more than 20,000_l._ Bishop Watson died on the 4th of June, 1816, in his seventy-ninth year. His writings are very numerous and miscellaneous in their character; some of the more well known are:--an 'Apology for Christianity,' written in 1776 in answer to Gibbon; a 'Collection of Theological Tracts, selected from various Authors, for the use of the Younger Students in the University,' in six volumes 8vo., 1785; 'Apology for the Bible, in a series of Letters addressed to Thomas Paine,' 1796; and, 'An Address to the People of Great Britain,' which went through fourteen editions, 1798.