I am trying to get my head around the events of 10-30 May 1940 and what happened to RAF ground units - the men supporting aircrew or those serving at HQ units. To my uneducated interpretation of events the majority of these seem to have been in northeast France facing the Franco-Belgium border, and should have been trapped by the German flanking movement through the Ardennes which reached Noyelles-sur-Mer on the Channel coast on 20 May.

The evacuation of the trapped BEF from the Channel ports of Calais, Boulonge and Dunkirk has been described many times, but relatively little appears to have been said about the men who escaped westwards via Brittany and Normandy.

Could anyone suggest a good book, or any account, which describes the story of these men (particularly the RAF) and their retreat westwards?

I apologise for showing my ignorance, but I have a number of meteorologists who took this route from the Arras/Lens areas, rather than via the northern Channel ports and I really want to know why they took that option.