By June 1940, advancing German forces were approaching
PC Bruno. Just after midnight on 10 June, Bertrand evacuated the
Bruno staff from Gretz-Armainvillers.
France surrendered on 22 June; on 24 June he flew the 15 Poles and seven Spaniards in three planes to
Algeria.
To put it another way, Bertrand was among those who were planning on the French government moving to Algeria and fighting on from there, like the people aboard the ship
Massilia. Accordingly, they flew out to Algeria.
What I don't understand about the story is who was getting the take from their activities. Before the evacuation they had a direct teletype link to Bletchley Park. Afterwards?