Son of the Rev. Peter Rounsefell (1820-1877; e.m. 1845), he was born at Shebbear and, following his father's early death, brought up by his mother in Plymouth. With the help of a scholarship, he was educated at Shebbear College 1881-1887. By private study he obtained a London BA in Classics (1896) and a BSc (1903), despite his lack of enthusiasm for the sciences. From 1890 he taught at the Hoe Grammar School, Plymouth, with a reputation for being a keen cricket player and an expert at chess. In 1909 he became headmaster of Shebbear College, in succession to the long reign of T. Ruddle, teaching most subjects in the curriculum as the need arose. History and Latin remained his first love. He retired in 1933. He was much in demand as a very able local preacher and served on the BC local preachers' Central Board. He is said to have been 'a rigid Puritan, but not of the straight-laced type'.
Two of his brothers entered the BC ministry: Digory Joseph Rounsefell ( ? - 1927; e.m.1890) and Owen Peter Rounefell (1874-1934; e.m. 1898).
'He was as great a contrast to Ruddle as it is possible to imagine. There was no show of the learning which he so lightly carried... He allowed nothing to be scamped, and would take unending pains with either a backward boy or a pupil of unusual promise. He never scolded, but boys feared his rebuke which had an acidity that bit into their soul. In class he used to jingle a few coppers or a bunch of keys that seemed to be kept for the purpose in his coat pocket... For nineteen years John Rounsefell held his gentle and undisputed sway at Shebbear; his name is now mentioned with reverence by men who are scattered over the globe. There is only one verdict, and that is that John Rounsefell was as good as he was great, a man of gentle manners but in moral fibre as strong and unyielding as steel.'
Richard Pyke, Men and Memories(1948) pp.87-9