The danger if Germany had captured the French fleet

How serious would it have been if Germany had taken control of the French fleet?

It would have been a severe additional problem, though French material limitations meant Britain could probably still have survived it.

German control of the French fleet would have been a major adverse contingency rather than an automatic British defeat. The ships would have enlarged the Axis naval problem at a moment of extreme pressure. Their technical and maintenance condition would still have limited what Germany could extract from them. British leaders were therefore unwilling to rely only on assurances that the fleet would remain unavailable to the Axis.