The Swann you are referring to sounds like Sidney Swann who rowed for Cambridge in the Boat Race 1883-5 and went on to become something of a muscular Christian. See Who's Who about 1940. Sidney Swann went a bit dotty, attempted to murder his wife, Lady Bagot, and was committed to an asylum whence he escaped and, after skulking around his home village, eventually moved back in to his old house. Lady Bagot eventually died and Rev Swann remarried and himself died after falling off his bicycle in 1942. Among his many rather extraordinary achievements, Sidney Swann rowed across the Channel in a boat he built himself, setting the record of 3 hrs 50 mins, which stood until 1983.
His son, S E Swann, went on to row for Cambridge himself from 1911-14 and stroked the boat in the 1912 Boat Race when Cambridge sank (12 days before the Titanic). He won a Gold Medal at the Stockholm Olympics in 1912 in the GB VIII. S E Swann also joined the church and went on to become Chaplain of Trinity Hall, Cambridge and a noted coach of the University Boat Club in the inter-war years.