RAF Fighter Command was now beginning “Rhubarb raids”, offensive attacks across the English channel by small numbers of fighter aircraft, sometimes just a pair, intended to strafe targets of opportunity. These were hazardous operations, often at the limits of range, with the added danger inherent in crossing the channel twice. Losses quickly mounted:
Our fighter patrols operated over Northern France on five days. Few enemy aircraft were encountered, but A.A. fire was generally heavy and accurate. On the 25th and 26th, an escort and screen was provided for a small bomber force which attacked shipping targets at Dunkirk and Calais. About 100 fighters were employed on each occasion.
From the Air Situation Report for the week see TNA CAB 66/15/19.