In short: no. The BEF was not the entire British professional army, as significant portions of the army were, as per the needs of imperial defence, deployed elsewhere in the empire. This included, for instance, the Western Desert Force, which consisted of 7th Armoured Division, 4th Indian and 7th (soon to be 6th) Infantry Division, all of them understrength, who were deployed in readiness for a suspected strike by Mussolini from Italian Libya, and which materialised on 10 June 1940, less than a week after the end of Operation Dynamo.

However, while it is an exaggeration to state that the BEF was Britain's 'entire professional soldiery', it is not too far from the truth either. Immediately after the outbreak of war, four British divisions were dispatched to France as the initial cadres of the BEF; these four divisions represented 2/3 of Britain's peacetime soldiery. These were to be reinforced by the reserve forces, the Territorials, throughout the early months of 1940, bringing the BEF up to ten frontline divisions, a number somewhere around half the size of the British army (including territorials and those conscripted into training) overall. Moreover, the BEF also had most of the British army's equipment; a large proportion of its motorised transport, virtually all of its available tanks, massive amounts of artillery, small arms, and other such materiel were largely held by the BEF, as the paucity of peacetime production had left the Army with few stores to fall back on. As Fletcher termed the period following Dunkirk, and the loss of so much equipment, abandoned on the beaches, 'the cupboard was bare'. As such, the hyperbole of Britain's 'entire army' being at risk can be forgiven.