All nine of the Grenfell brothers were expert polo players. Francis and his brother Riversdale Grenfell were regarded as the best in the family. Francis was rated at an 8 goal handicap. The twin brothers were on the Ranelagh team that won the American Open. And they were on the team Freebooters, alongside Leopold Christian Duncan Jenner and the Duke of Roxburghe, that won the Hurlingham Champion Cup.