In Richard Collier's Eagle Day - BoB he covers 303 Squadron - Polish aviators, among many other RAF and Luftwaffe units, throughout the battle. RAF had the Poles tasked w/ learning English, afraid that their poor English would interfere w/ combat ops. They were stuck in training flights, until a training flight bumped into a raid, and Poles peeled off the formation and attacked. From that day on they were fully operational.