In January 1825 Sir Astley resigned his lectureship at St. Thomas’s, owing to the impairment of his health. Mr. Key had previously been delivering part of his surgical course, and his nephew Bransby Cooper had undertaken the anatomical lectures; and Sir Astley was determined to secure their succession to his appointments. He had only resigned in the firm conviction that this was generally agreed upon. His astonishment may be imagined when he learnt that Mr. South had been appointed anatomical lecturer. Sir Astley, desiring to withdraw his resignation, was informed that it was too late. Mr. Harrison, however, the then spirited treasurer of Guy’s, came to the rescue, and offered to establish a school of medicine at Guy’s, totally independent of St. Thomas’s, and to appoint Mr. Key and Mr. Bransby Cooper to the chairs of surgery and anatomy. This was at once agreed to, and a lecture theatre and other premises hastily built during the summer, so that the new school of Guy’s was opened in the succeeding October. A large proportion of the old pupils of the united schools of St. Thomas’s and Guy’s entered at Guy’s, and a considerable number of new pupils coming up, the now famous school was prosperously floated. Sir Astley did not lecture much for the new school, though he gave a few occasional lectures on anatomy and surgery, which of course were crowded to excess. He now became consulting surgeon to Guy’s, and evidenced his zeal by commencing the formation of a museum like that which he had already deposited at St. Thomas’s, and which he would have removed thence had it been in his power. In 1827 he was elected President of the College of Surgeons. By this time Sir Astley had adopted the habit of spending as much of his time as possible on his estate at Gadesbridge, near Hemel Hempstead. Here he became a rural character, shooting and “making shoot” with eagerness and joviality. Lady Cooper, having lost her adopted daughter, Mrs. Parmenter, and having had no second child, could not endure living in London. In 1825, Sir Astley took his home-farm upon his hands, and kept it in consummate order, at considerable expense, it must be owned. He was always either experimenting or trying to carry out some new plan he had heard of or observed. He again and again became violently angry, as he grew older, when he found that his ideal farm only produced substantial loss: and used repeatedly to vow he would never allow such passion to overcome him again. One of his experiments in farming was the purchase of lame or ill-fed horses at Smithfield at from five to seven pounds apiece, feeding and doctoring them himself at Gadesbridge, and turning them into much better animals. He sometimes made a good profit in this way, and for years drove in his own carriage horses that had only cost him twelve pounds ten. If they were past cure, he would experiment upon them according to what investigation he might have in progress at the time.