What a mass French fleet escape might have changed

A mass departure of French ships in 1940 could have given the Allies a major early increase in naval strength. The counterfactual includes ships outside France and others able to escape, carrying as many troops and other personnel as possible. That departure would also have deprived Vichy France of a major asset. The dilemma is that keeping the fleet outside Allied operations also benefited the Axis, even while the ships remained outside direct Axis control.