Here is a good little piece, credits below...

The evacuation from Dunkirk, codenamed "Operation Dynamo, " commenced on 26 May. It was originally hoped that up to 45,000 men might be rescued. The actual total came to 338,000 men.
Lord Gort was instructed not to inform his French and Belgian colleagues that the evacuation was beginning. South-east of Dunkirk the British withdrew their units, leaving seven French divisions alone to face the advancing Germans. The French fought on until their ammunition was exhausted and managed, like the Belgians, to tie down German forces that would otherwise have been available to assault the perimeter of Dunkirk.
As British and French troops retired toward Dunkirk, Admiral Sir B.H. Ramsay organized the sea lift to England. After the French government protested, a written order was issued commanding that French troops be embarked in equal numbers with the British. In practice this was not carried out. Harmon records that when Frenchmen tried to board boats on the beach, Royal Navy shore parties organized squads of soldiers with fixed bayonets to keep them back. On at least one occasion a British platoon fired on French troops attempting to embark. Only after practically all the British had escaped were efforts made to evacuate the remaining French soldiers. But when the port surrendered to the Germans on 3 June, over 40,000 French soldiers were captured.
Perhaps the most memorable aspect of the evacuation was the role played by civilians in their small boats. Harmon explains that this is just part of the myth. The British public was not informed that an evacuation was underway until 6pm on 31 May. A Small Vessels Pool, based on Sheerness, did assemble a large number of small civilian craft. But most of them were useless for evacuation work. Only on the last two days of the withdrawal did civilian volunteers play a role in rescuing an additional 26,500 men from the beaches. Their contribution, notes the author, "was gallant and distinguished; but it was not significant in terms of numbers rescued."
From:
The Miracle of Dunkirk Reconsidered
CHARLES LUTTON
Dunkirk: The Patriotic Myth by Nicholas Harmon. New York: Simon & Schuster, 1980. 271 pp. with appendices