The son of a Thames waterman, it was perhaps inevitable that Harry Barnsley would also take to the water, and he went on to enjoy a long career with the Weybridge Rowing Club. As a 17-year-old, he coxed their junior fours before progressing to senior crews. Having missed out when the Weybridge boat was beaten by Thames RC in the Olympic trial to see who should represent Great Britain in the eights at the 1924 Paris Olympics, Barnsley was cox to the Great Britain fours at the Games, but they finished second in both their heat and repêchage. Two months after the Olympics, Barnsley won the NARA coxed double sculls with W. A. Wigmore and Jack Townend at the Walton-on-Thames regatta. Barnsley served on the committee of Weybridge Rowing Club for many years.